Surveys about the use of drugs for neuroenhancement in the workplace are very rare. A recent survey among surgeons by Franke and colleagues found a lifetime prevalence rate of 9% for the use of prescription and illicit drugs, 13% for caffeine tablets, and 24% for caffeinated drinks (which describes the mainly German term "Energy drinks" included in the upper most cases caffeine and taurine, excluding cola drinks; Franke et al., 2013, 2015a). Using a technique for increased confidentiality during the assessment (randomized response technique, RRT Campbell, 1987; Moshagen et al., 2010), the group found a lifetime prevalence rate for prescription and illicit drugs of 20% (Franke et al., 2013). A survey by the German DAK found a lifetime prevalence rate of 3.3% for "neuroenhancement" and 4.7% for "neuroenhancement to increase mood or to reduce anxiety and nervousness" [Deutsche Angestelltenkrankenkasse (DAK), 2015]. The KOLIBRI study found a last-year prevalence of 1.5% for all prescription drugs (beta-blockers, stimulants, MPH, antidementia drugs, antidepressants, and modafinil) and 1.0% of which was attributed to antidepressants [Robert-Koch-Institut (RKI), 2011]. The most recent survey concerning neuroenhancement in the workplace using an anonymizing technique revealed a 12-month prevalence rate of 15.4% for the use of prescription drugs among 1186 employed persons (mostly teachers) in Jordan (Wolff et al., 2015). Furthermore, a survey study by Franke and colleagues in 3300 surgeons showed that reducing fatigue, working the night shift and excessive work hours were frequent reasons for using PN substances. This seems to show that coping with unfavorable working conditions such as "stress" are important reasons for using PN drugs (Franke et al., 2013, 2015a). Among students, stress periods in the scope of preparation for exams are associated with the use of PN drugs Burgard et al., 2013). However, among teachers, the willingness of using PN drugs was shown to be low (Sattler et al., 2013; Wiegel et al., 2015). The recent DAK study among 5000 employees showed lifetime prevalence rates of 3.3% for "neuroenhancement" and 4.7% for "neuroenhancement to increase mood or to reduce anxiety and nervousness" [Deutsche Angestelltenkrankenkasse (DAK), 2015].

Numerous studies with divergent study designs have been performed with the group of drugs considered to be neuroenhancers (Mehlman, 2004; De Jongh et al., 2008) to assess the efficacy of the candidate drugs (Solomon et al., 2002; Wesensten et al., 2002; Yesavage et al., 2002; Breitenstein et al., 2004; Killgore et al., 2008, 2009). Overall, the group of stimulants—methylxanthines, e.g., caffeine, and amphetamines, e.g., MPH—seems to have broad pro-cognitive effects on simple cognitive domains that can be affected in fatigued persons. Furthermore, some studies indicate pro-cognitive effects on certain higher cognitive domains, such as particular memory domains. In addition, euphoric effects (in the scope of mood neuroenhancement) of amphetamines have to be considered. (Repantis et al., 2010a,b; Kelley et al., 2012; Franke et al., 2014).

The present web-based study design was inspired by the above mentioned Nature poll with the aim to raise data from persons who work in the field of economics or economic-related studies. Therefore, the study assessed for the first time the use of potential neuroenhancers based on an online poll posted on the homepage of the "Handelsblatt" in order to capture data of their readers.

We hypothesized that the prevalence rates of drug use for neuroenhancement within the field of economics as well as associated factors would be similar to previous studies in students, physicians and scientists.

# MATERIALS AND METHODS

The present survey was designed on the basis of the Nature poll by Brendan Maher (Maher, 2008). We chose to advertise the survey in the German "Handelsblatt," a print and online medium for people working in the field of economics. The Handelsblatt, which until 2005 was part of the company that publishes the Wall Street Journal in the US, is the leading economics journal in German-speaking countries; its print run in 2014 was 120,000 and in Germany it is the most cited print medium for economics (Handelsblatt). Readers of the online edition of the Handelsblatt were invited to participate in the present survey via a link on the homepage of the journal (www.Handelsblatt.com)1 .

#### Data Acquisition

To ensure a high degree of privacy and anonymity, the survey was designed as an online poll with eight closed questions about participants' characteristics and their patterns of drug use for neuroenhancement. The survey was open for participation during the last 2 weeks of December 2014. Before starting the survey, readers read a short introductory paragraph that introduced them to the topic of neuroenhancement and explained the survey. Then, after answering questions about their gender, current age, current professional status, and hours of work per week, participants were asked if they would at all consider using (a) legal over-the-counter drugs (OTC drugs) (b) prescription drugs, or (c) illicit drugs for neuroenhancement or (d) no drugs for enhancement at all. Directly afterwards, participants were asked to indicate any substances they had already used for neuroenhancement by completing a table that listed OTC drugs and prescription and illicit drugs as well as drinks known to be frequently used for neuroenhancement by students (Mehlman, 2004; De Jongh et al., 2008; Franke et al., 2011b, 2014; Dietz et al., 2013b; Schelle et al., 2015) and surgeons (Franke et al., 2013, 2015a): coffee, energy/caffeinated drinks, caffeine tablets, cola drinks, Ginkgo biloba, Ritalin R , Adderall R , modafinil, ecstasy, ephedrine, cocaine, crystal meth, illicit amphetamines, and antidepressants. Subsequently, participants were asked which of the following situations and reasons were associated with their use of the aforementioned drug or drugs for neuroenhancement (multiple responses were possible): (a) curiosity, (b) stress/pressure to perform, (c) tiredness, (d) to enhance mood, (e) for a confident appearance, (f) deadline pressure, (g) other; these categories were identified in previous studies in students as reasons and situations commonly associated with the use of drugs for neuroenhancement.

In order to exclude from further analysis participants who used certain prescription drugs to treat a disease, participants were asked if they suffered from attention-deficit-hyperactivity disorder (ADHD) or depression. Participants who stated to "have been diagnosed" with ADHD or depression were excluded.

#### Data Analysis

Data were collected in a database connected directly to the survey questionnaire. Statistical analyses were performed with SPSS for Windows, version 22.0. Binary regression analysis with stepwise forward selection was used to predict the dependent variables "use of illicit and prescription drugs for neuroenhancement" (yes/no), "use of OTC drugs for neuroenhancement" (yes/no), and "use of any drug for neuroenhancement" (yes/no). Continuous variables (age, hours of work per week) were dichotomized by mean. Results are given as means and standard deviations (SD), prevalence rates (%), or odds ratios (OR) with Clopper-Pearson confidence intervals (95% CI) and p-values.

# Ethics Statement

The study was performed according to the Declaration of Helsinki. Participants gave informed consent by clicking on a button after reading the short introductory paragraph and by pressing the button "done" at the end of the survey. The study was approved by the responsible ethics committee (Greifswald; approval no. BB 095/14).

# RESULTS

In total, 1021 readers of the journal Handelsblatt participated in the survey. Among the participants, 6.6% (n = 67) reported to have been diagnosed with ADHD or depression and had to be excluded from further analysis. Therefore, the data of 954 participants were analyzed. Most of the participants were male (82.7%), with a mean age of 36.3 years. Approximately onethird of the participants rated themselves as belonging to "middle management" (32.4%). Participants worked aF mean of 48.7 h per week. **Table 1** gives a detailed description of participant characteristics.

Regarding the question of whether the participants would consider using any substance for neuroenhancement, 40.0% (n = 372) answered "yes, an OTC substance," 12.6% (n = 117) answered "yes, a prescription drug" and 8.3% (n = 77) answered "yes, an illicit drug."

Among all participants, 88.0% (n = 831) had used one of the listed substances (see Materials and Methods Section) for neuroenhancement purposes at least once in their life (lifetime prevalence): lifetime prevalence was 87.5% (n = 824) for the use of any OTC drug for neuroenhancement and 19.0% (n = 171) for the use of any prescription or illicit drug for neuroenhancement. Among the group of OTC drugs and drinks the most commonly used substance was coffee (lifetime prevalence: 77.1%, n = 723),

TABLE 1 | Basic characteristics of the survey participants.

1According to a personal communication from the Handelsblatt and www.Handelsblatt.com (accessed in april 2015) and www.ivw.eu (accessed in april 2015).

followed by cola drinks (Coca-Cola R , etc.; lifetime prevalence: 56.6%, n = 521; see **Table 2**). The most frequently used drugs among the group of prescription and illicit drugs were antidepressants, with a lifetime prevalence of 7.2% (n = 65) and a period prevalence rate in the last month of 2.0% (n = 18); during the last month only cocaine was used more frequently (2.3%, n = 20; **Table 2**). For more detailed information about prevalence rates, see **Table 2**.

The most frequently mentioned situations or reasons associated with using any drug for neuroenhancement including OTC and prescription and illicit drugs were "tiredness" (79.4%, n = 533), "stress/pressure to perform" (41.7%, n = 280), and "to enhance mood" (22.2%, n = 149). The rates for "deadline pressure," "curiosity," "for a confident appearance," and "others" were 17.3% (n = 116), 12.2% (n = 82), 11.8% (n = 79), and 11.5% (n = 77), respectively; **Table 3** gives further details about situations or reasons associated with the use of OTC drugs and prescription and illicit drugs.

Binary logistic regression revealed five independent variables that predict the use of illicit and prescription drugs for neuroenhancement: "curiosity," "stress/pressure to perform," "to enhance mood," "for a confident appearance," and "deadline pressure" (see **Table 4**). The dichotomized independent variables "age" and "hours of work per week" as well as each of the items "current profession," "using OTC drugs for neuroenhancement," "gender," and "tiredness" did not significantly predict the use of illicit and prescription drugs for neuroenhancement. Only two independent predictor variables, "tiredness" and "stress/ pressure to perform," were found for OTC drug use for neuroenhancement and for the use of any substance for neuroenhancement (including OTC, illicit and prescription drugs), respectively (see **Table 4**).

The areas under the receiving operation curve (ROC) of the overall regression models were 77.2% for "use of illicit and prescription drugs for neuroenhancement," 85.5% for "use of OTC drugs for neuroenhancement," and

TABLE 2 | Prevalence rates for use of substances for neuroenhancement among survey participants (N = 954).

*AMPH, amphetamines; "ever," within the last month* + *within the last 12 months* + *more than 12 months ago; OTC drugs, over-the-counter drugs.*

*OTC drugs, over-the-counter drugs.*

88.1% for "use of any substance for neuroenhancement," respectively.

#### DISCUSSION

This study used an anonymous web-based questionnaire to investigate for the first time the use of drugs for neuroenhancement among the "Handelsblatt" readership working or at least studying in the field of economics. The study shows that the prevalence rates of neuroenhancement in the surveyed participants within the field of economics are similar to those in other highly demanding fields. Although, the associated reasons and situations are somewhat similar, non-cognitive reasons for neuroenhancement are much more important in our participants than among the previously studied groups (students, surgeons).

Among the large number of papers on neuroenhancement, one of the most extensive studies (in 8000 students) found lifetime prevalence rates of 5% for prescription drugs and 5% for so-called "soft enhancement" (use of vitamins, homeopathic drugs, "herbal" substances, caffeine, etc.), i.e., significantly lower rates than that in our study (40.0%; Middendorff et al., 2012).

There is a paucity of data about neuroenhancement among the general population and employed persons in particular. For their 2015 health report, a German health insurance company (DAK) re-assessed a representative panel of 5000 participants aged between 20 and 50 years [Deutsche Angestelltenkrankenkasse (DAK), 2015]. The online study had a response rate of 49.1% and found lifetime prevalence rates of 3.3% for "neuroenhancement" and 4.7% for "neuroenhancement to increase mood or to reduce anxiety and nervousness" [Deutsche Angestelltenkrankenkasse (DAK), 2015]. Cognitive neuroenhancement was more frequent among men, and mood neuroenhancement, as well as reduction of anxiety and nervousness, more frequent among women

#### TABLE 4 | Predicting factors for the use of substances for neuroenhancement.

*Odds ratios for the dependent variables "use of illicit and prescription drugs for neuroenhancement," "use of OTC-drugs for neuroenhancement," and "use of any substance for neuroenhancement" and each predictor variable (stepwise, forward regression). Levels of significance: p* < *0.05*\**; p* < *0.01*\*\**; p* < *0.001*\*\*\**; (CI, confidence interval; OR, odds ratio); OTC drugs, over-the-counter drugs.*

[Deutsche Angestelltenkrankenkasse (DAK), 2015]. This finding is in contrast to our study results. We found significantly higher prevalence rates and no differences between men and women regarding special patterns of substance use which may be due to the inequal preponderance in our study in contrast to the DAK study. However, in line with the DAK study we found higher prevalence rates for mood neuroenhancement than for cognitive neuroenhancement, which we consider to be one of the most important findings of our study.

The Kolibri study evaluated 6000 participants from the general public and found a last-year prevalence of 1.5% for all prescription drugs (beta-blockers, stimulants, MPH, antidementia drugs, antidepressants and modafinil), 1.0% of which was attributed to antidepressants [Robert-Koch-Institut (RKI), 2011]. The relatively high prevalence rates for the use of potential mood-enhancing substances concur with our findings.

One German web-based study used vignettes to examine the prevalence rate of neuroenhancement among university teachers and their willingness to use drugs for neuroenhancement and found both to be low (Sattler et al., 2013; Wiegel et al., 2015). However, teachers are not comparable with the participants surveyed in this study.

The Nature poll mentioned above found a lifetime prevalence rate of 20% for the use of beta-blockers, methylphenidate (MPH; Ritalin R ), and modafinil (Maher, 2008) which is nearly the same as that found among the participants of the present survey (19.0% lifetime prevalence rate for prescription and illicit drug use). Ritalin R was the most commonly used drug in the Nature poll, and in our study lifetime prevalence rates were highest for illicit amphetamines. Considering that MPH belongs to the group of amphetamines and Ritalin R was the third most frequently used prescription/illicit drug in our survey, the results are again comparable. Beyond the question of the frequency of use for neuroenhancement, Maher found that the most popular reasons for the use of the three assessed drugs were to improve concentration, improve focus for a specific task, and counteract jetlag (Maher, 2008). Interestingly, these reasons do not overlap with those found in our study, which identified curiosity, mood neuroenhancment, and confident appearance as the three most important reasons for neuroenhancement.

Franke et al. studied 3300 surgeons and found a lifetime prevalence rate for the use of prescription and illicit stimulants of 8.9% when participants completed a direct questioning survey (paper-and-pencil questionnaire) and 19.9% when the specialized anonymizing survey technique RRT was applied (Franke et al., 2013, 2015a). Furthermore, lifetime, past-year, past-month, and past-week prevalence rates for coffee were 66.8, 61.9, 56.9, and 50.5%, for caffeinated drinks 24.2, 15.4, 9.9, and 6.1%, and for caffeine tablets 12.6, 5.9, 4.7, and 3.8%, respectively. Although, prevalence rates for coffee were similar to those in the present study, those for caffeinated/energy drinks and caffeine tablets were significantly lower (Franke et al., 2015a). Prevalence rates for (psycho-) stimulants were higher among surgeons than in our study (Franke et al., 2013).

Among surgeons, reducing fatigue (54.3%), working the night shift (32.2%), and overly long and excessive work hours (31.7%) were the most frequent reasons for using caffeine (Franke et al., 2013). This finding could only be partially confirmed in the present study, which identified tiredness, stress/ pressure to perform, and mood neuroenhancement as the three most important reasons for using caffeine.

When Franke and colleagues compared the use of prescription and illicit drugs by surgeons for cognitive neuroenhancement with the use of antidepressants for mood neuroenhancement, which was a separate category in the study, they found lifetime prevalence rates of 8.9% for the former and only 2.4% for the latter (Franke et al., 2013). Our study found much higher prevalence rates for antidepressant use without medical need (7.2%, n = 65), i.e., the rate was three-fold higher among the present participants. The reason for this discrepancy is unclear. Therefore, future studies should address in detail the reasons why participants use drugs for the purpose of neuroenhancement and for mood enhancement.

The question of anonymity and privacy when using a survey about potentially stigmatizing issues is complex. Empirical social science has shown a tendency for people to answer with socially desirable answers when asked about sensitive or stigmatizing issues (e.g., own thievery; Schnell et al., 1992). This aspect is important when asking participants about their use of neuroenhancement drugs which, at least in the case of misusing prescription drugs and using illicit drugs, is potentially punishable. Therefore, other studies using the RRT—which is only one among a variety of techniques for the assessment of socially undesirable behavior (Campbell, 1987; Moshagen et al., 2010; Wolff et al., 2015)—to assess the use of antidepressants among surgeons, found prevalence rates of 19% for cognitive neuroenhancement and 15% for mood neuroenhancement. Prevalence rates for cognitive neuroenhancement are comparable to our results; however, prevalence rates for mood neuroenhancement are considerably higher. Comparable prevalence rates for neuroenhancement may imply that an online poll gives a subjective feeling of anonymity and privacy similar to the RRT, perhaps because (more or less) nobody can trace answers back to the participants.

Taken together, the high discrepancy between the direct questioning and RRT results for antidepressants and the high prevalence rates for the use of antidepressants found in the present study could mean that mood neuroenhancement and not cognitive neuroenhancement is the "core enhancement" phenomenon. Because stimulants also have euphoric effects, they are perhaps being used for both purposes. An as yet underestimated reason could be to feel more self-confident and to enhance mood. Even though this assumption is highly speculative, it is supported by the present study and may therefore warrant further investigation.

In addition to the aspects mentioned above, some factors should be addressed that limit the explanatory power of this study. As with every survey study, one can discuss the suitability of the content and length of the questionnaire and the likelihood of complete participation. Our questionnaire, inspired by the online Nature poll (Maher, 2008) was designed to increase the likelihood of participation and the completeness of participants' responses at the expense of losing a large amount of information because of its brevity. Therefore, the authors designed the questionnaire on the basis of the available neuroenhancement literature to be brief but nevertheless informative. A webbased survey has an inherent risk of participation bias because one cannot control for participants' experiences, opinions, personal characteristics, and subjective aims when answering the questions. Nevertheless, we considered such a survey the best way to collect "real life" data and gain insight into the fast-paced field of economics.

The main strength of this study, its high degree of anonymity and privacy, is also the cause of one of its most **limiting factors**, the participation bias. Because the present study was voluntarily conducted as an online poll—to guarantee the highest degree of anonymity and privacy—in the Handelsblatt, readers of the online version of this specific journal were able to participate. However, because of the possibility to distribute links via social media networks, it cannot be guaranteed that only readers of the Handelsblatt participated. This may explain the fact, that the group of participants is more or less heterogeneous. Means to reduce participation bias and to control for participation (e.g., via participation codes, etc.) leads to reduced anonymity and privacy and were not considered by the authors in order to receive honest answers. This major limitation was of similar concern in the Nature poll by Brendan Maher.

Beyond that, the online version is widely read and only ∼1000 individuals participated, which may not be representative of only those working in the field of economics. Furthermore, we have no information about possible specific characteristics of the individuals who did not participate. Therefore, we do not know whether those individuals would have increased or decreased the prevalence rate for neuroenhancement or shown additional predictors. Online surveys cannot control for such a disproportion and response bias.

In sum, the study results presented here show that drug use to increase cognition, enhance mood, improve confidence, or cope with stress and pressure seems to be a widespread phenomenon within the field of economics. Taken together, the results of this and previous studies indicate that the findings of studies in high school, college, and university students may also be valid in employed persons. Findings in employed persons such as surgeons, individuals working in the professional field of economics, and natural scientists demonstrate that neuroenhancement has become a widespread phenomenon. Both are associated with health concerns, because any (mis-) use of drugs may have adverse effects on mental and physical health. For example, any stimulant is associated with the risk of cardiovascular events, hypertonia, tachycardia, and even sudden cardiac death (e.g., Kumar, 2008; Ali et al., 2015; Vetter et al., 2015). Such events may be more frequent when drugs are misused without a physicians' prescription or are mixed with other drugs. Additionally, drug misuse can lead to addiction and be a gateway for the use of other—more harmful or illicit drugs (Kandel, 2002; Dietz et al., 2013b, 2016). Taking these negative aspects together and considering the high prevalence rates of drug use for neuroenhancement, we think that the creation of prevention programs and related educational material is of great public health relevance. A large journal with an online version like the Handelsblatt, which is read by a potential at-risk population, could be used to spread information and material about such programs. Additionally, the predictors for drug use for neuroenhancement identified in the present study may help to create well-directed prevention programs

# REFERENCES

and education material tailored more closely to individual needs. As the metric scaled variables in the present study were dichotomized for analyses, one implication for future studies would be to provide more individual profiles of drug users, addressing more specific demographic characteristics, rather than the dichotomized method used in the current study.

# AUTHOR CONTRIBUTIONS

AF made substantial contributions to the conception and design of the study, the data acquisition, analysis, and interpretation of data, and the preparation of the manuscript. MS made substantial contributions to the interpretation of data and the preparation of the manuscript. PD made substantial contributions to the analysis and interpretation of data and the preparation of the manuscript. All authors proofread and accepted the final version of the manuscript.

#### ACKNOWLEDGMENTS

There was only intramural funding of this project. The authors want to thank the German Handelsblatt and especially Jörg Hackhausen for the distribution of the survey. The authors also thank Jacquie Klesing, Board-certified Editor in the Life Sciences (ELS), for editing assistance with the manuscript. Additionally to Jacquie Klesing, we further thank Estelle Watson for improving the readability of our manuscript.

**Conflict of Interest Statement:** The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Copyright © 2016 Dietz, Soyka and Franke. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

# Associations Between the Big Five Personality Traits and the Non-Medical Use of Prescription Drugs for Cognitive Enhancement

#### Sebastian Sattler 1 \* and Reinhard Schunck 2

*1 Institute of Sociology and Social Psychology, University of Cologne, Cologne, Germany, 2 Faculty of Sociology, Bielefeld University, Bielefeld, Germany*

#### Edited by:

*Ralf Brand, University Potsdam, Germany*

#### Reviewed by:

*Boris B. Quednow, Psychiatric Hospital, University of Zurich, Switzerland Lambros Lazuras, Sheffield Hallam University, UK*

> \*Correspondence: *Sebastian Sattler<EMAIL_ADDRESS>
#### Specialty section:

*This article was submitted to Performance Science, a section of the journal Frontiers in Psychology*

Received: *14 September 2015* Accepted: *09 December 2015* Published: *05 January 2016*

#### Citation:

*Sattler S and Schunck R (2016) Associations Between the Big Five Personality Traits and the Non-Medical Use of Prescription Drugs for Cognitive Enhancement. Front. Psychol. 6:1971. doi: 10.3389/fpsyg.2015.01971* While the number of studies of the non-medical use of prescription drugs to augment cognitive functions is growing steadily, psychological factors that can potentially help explain variance in such pharmaceutical cognitive enhancement (CE) behavior are often neglected in research. This study investigates the association between the Big Five personality traits and a retrospective (prior CE-drug use) as well as a prospective (willingness to use CE drugs) measure of taking prescription drugs with the purpose of augmenting one's cognitive functions (e.g., concentration, memory, or vigilance) without medical necessity. We use data from a large representative survey of German employees (*N* = 6454, response rate = 29.8%). The Five Factor Model (FFM) of Personality was measured with a short version of the Big Five Personality Traits Inventory (BFI-S), which includes: openness to experience, conscientiousness, extraversion, agreeableness, and neuroticism. Together with this, demographic variables such as gender, age, education, and income were used as potential confounders in multiple logistic regression models. Our results show a 2.96% lifetime prevalence of CE-drug use and a 10.45% willingness to (re)use such drugs in the future. We found that less conscientious and more neurotic respondents have a higher probability of prior CE-drug use and a greater willingness to use CE drugs in the future. No significant effects were found for openness, extraversion, or agreeableness. Prior CE-drug use was strongly associated with a greater willingness to take such drugs in the future. This study shows that specific personality traits are not only associated with prior enhancement behavior, but also affect the willingness to (re)use such drugs. It helps increase understanding of the risk factors of CE-drug use, which is a health-related behavior that can entail severe side-effects for consumers. The knowledge gathered can thus help improve interventions aimed at minimizing health problems.

Keywords: pharmaceutical cognitive enhancement, non-medical use of prescription drugs, substance abuse, drug misuse, five-factor model, personality traits

# INTRODUCTION

Personality traits, which can be described as differences between individuals regarding their behavior, thoughts, and feelings, can be seen as relatively stable in different situations and over time (Caspi, 1998; McCrae and Costa, 2008; Specht et al., 2014). These traits are important predictors of numerous personal, interpersonal, and social/institutional outcomes (Booth-Kewley and Vickers, 1994; Soldz and Vaillant, 1999). Among these are, for instance, happiness, physical and psychological health, longevity, criminal activity, and occupational choices (Booth-Kewley and Vickers, 1994; Ozer and Benet-Martinez, 2006; John et al., 2008). Personality traits (e.g., sensation seeking, neuroticism, impulsivity, anxiety) also seem to be variously associated with the use of different classes of substances and consumption intentions and therefore with risky health behavior that can have deleterious health consequences later in life (e.g., Herman-Stahl et al., 2006; Terracciano et al., 2008; Weyandt et al., 2009; Atherton et al., 2014; N'Goran et al., 2014; Maier et al., 2015).

In this study, we focus on the relationship between personality traits and the non-medical use of prescription drugs (e.g., methylphenidate, modafinil, donepezil) with the subjective aim of augmenting one's cognition (Glannon, 2008; Repantis et al., 2010; Smith and Farah, 2011). These drugs are usually prescribed to treat medical conditions, e.g., attention deficit disorder, narcolepsy, dementia, or Alzheimer's disease. This kind of cognitive enhancement (CE) can be defined as the intended or expected improvement of cognitive functions in healthy individuals in order to augment concentration, vigilance, memory, wakefulness, etc. (e.g., Bostrom and Sandberg, 2009; Repantis et al., 2010; Sattler and Wiegel, 2013) 1 . Given that clinical studies show that the effects of CE with current drugs are limited and sometimes even detrimental (Glannon, 2008; Repantis et al., 2010; Smith and Farah, 2011; Ragan et al., 2013), expectations regarding effectiveness seem often to be exaggerated (Repantis et al., 2010) while at the same time there are also potential risks in terms of side-effects and long-term health consequences (Sussman et al., 2006; Maher, 2008; Winder-Rhodes et al., 2010; Ragan et al., 2013). Beside these risks, the ethical debate about CE-drug use discusses several other potential negative consequences such as whether it undermines authenticity, amounts to cheating/is unfair, increases social inequality, results in direct or indirect coercion to also use such drugs, can burden the health care system, and can result in the involvement of the criminal justice system (Glannon, 2008; Greely et al., 2008; Bostrom and Sandberg, 2009; McLarnon et al., 2012; Dubljevic et al., 2014; Sattler, in press ´ ).

Despite the possible detrimental effects and (long term) side effects of CE (Sussman et al., 2006; Glannon, 2008; Maher, 2008; Repantis et al., 2010; Winder-Rhodes et al., 2010; Smith and Farah, 2011; Ragan et al., 2013), healthy individuals take such medication for enhancement purposes. In addition to several studies questioning students about their CE use (Middendorff et al., 2012; Maier et al., 2013; Sattler and Wiegel, 2013; Wolff and Brand, 2013; Singh et al., 2014), only a few have surveyed the general population including the working population or parts of it. An informal survey among 1400 readers of the magazine Nature reported that 20% have already used such drugs for non-medical reasons to improve concentration, focus, or memory; these include methylphenidate (like Ritalin), modafinil (like Provigil), beta blockers (like propranolol), and/or others (Maher, 2008). The reported 12-month prevalence in a representative German study was 1.5% for drugs used to increase cognition and/or mood including prescription drugs (e.g., drugs counteracting depression such as fluoxetin and/or beta blockers) and illicit drugs (i.e., chemically synthesized stimulants such as amphetamines; Hoebel et al., 2011). A German health insurance company's survey of employees covered under its plans found that 4.7% used such drugs (i.e., stimulants such as methylphenidate, antidementives such as donepezil, and/or antidepressants such as fluoxetin) during their lifetime to enhance cognition and/or mood (DAK Gesundheitsreport, 2009) in a follow-up study prevalence increased to 6.7%, whereby 3.3% used drugs for CE (Marschall et al., 2015). Among German university teachers fewer than 1% reported prior non-medical use of prescription drugs to enhance cognitive performance (without specifying drugs or drug classes); however, more than 10% were willing to use such drugs in the future (Wiegel et al., 2015). This elevated willingness could turn into behavior under certain conditions, e.g., improved benefit-risk ratio or easier access (Singh et al., 2014; Wiegel et al., 2015), which would contribute to the predicted trend of increased CE-drug use.

Existing prevalence estimates are very heterogeneous, however. This is mainly due to inconsistent methods and measures across studies (Smith and Farah, 2011; Ragan et al., 2013; Ford and Ong, 2014; Maier et al., 2015; Sattler, in press). Most studies are not based on probability samples, but instead use small-scale samples, special populations, or combine prescription and illicit drugs or mood and CE into a single category. Thus, to get better estimates of the prevalence of CEdrug use, large-scale population-based probability samples have been strongly recommended (Hoebel et al., 2011; Mache et al., 2012; Sattler et al., 2013a; Fitz et al., 2014; Sattler, in press). Given the potential negative consequences of CE-drug use mentioned above, more empirical data about prevalence are needed on a regular basis for decision-making about the regulation of these drugs (Ragan et al., 2013; Maier and Schaub, 2015) to be better informed and also because of the assumption that the spread of CE drugs on the world market and on the Internet can scarcely be stopped (Sahakian and Morein-Zamir, 2007). More importantly, however, it is necessary to develop a better understanding of the antecedents to CE as a risky health-related behavior in order to inform prevention policies and to develop interventions for reducing its potential negative consequences (Booth-Kewley and Vickers, 1994; Terracciano et al., 2008).

While we can observe an increase in the number of studies that explore social, personal, and the characteristics of the

1 In our study, we focus on prescription drugs that seem to dominate the current debate (e.g., Farah et al., 2004; Glannon, 2008; Greely et al., 2008; Racine and Forlini, 2010; Smith and Farah, 2011; Ragan et al., 2013; Schelle et al., 2014; Sattler, in press). Among these are drugs such as prescription stimulants (e.g., methylphenidate), antidementives (e.g., donepezil), and antidepressants (e.g., fluoxetine). The term "cognitive enhancement" generally encompasses the use of various potential enhancement means such as illegal drugs (e.g., cocaine), overthe-counter drugs (e.g., guarana), drugs naturally synthecized in the body (e.g., insulin), but also non-substance-based means such as mental training, sleep, brain stimulation (e.g.,Bostrom and Sandberg, 2009; Dresler et al., 2013).

substances as correlates of CE-drug use and willingness to use CE (Sattler and Wiegel, 2013; Wolff and Brand, 2013; Sattler et al., 2013a,b; Dubljevic et al., 2014; Ford and Ong, 2014; ´ Singh et al., 2014; Wolff et al., 2014; Maier et al., 2015; Wiegel et al., 2015), we still know very little about the role of psychological variables in relation to CE, in particular how personality characteristics affect CE-drug use. Accordingly, researchers have called for more studies on the effects of psychological variables (Quednow, 2010; Schelle et al., 2014; Wolff et al., 2014; Ponnet et al., 2015). Previous studies, for example, found that high achievement motivation (Franke et al., 2012), the inclination to procrastinate (Sattler et al., 2014; Ponnet et al., 2015), risk attitudes (Sattler and Wiegel, 2013; Sattler et al., 2014), stress (Wolff and Brand, 2013; Wiegel et al., 2015), high pressure to perform (Franke et al., 2013), cognitive test anxiety (Sattler and Wiegel, 2013; Sattler et al., 2014), trait impulsivity (Maier et al., 2015), Machiavellianism (Maier et al., 2015), novelty seeking (Maier et al., 2015), lower cognitive empathy (Maier et al., 2015), and burnout (Wolff et al., 2014) were positively associated with CE-drug use or willingness to use. Our study aims at increasing our knowledge about the antecedents of CE-drug use by further investigating the relationship between personality characteristics and CE. Since it is advisable to employ multidimensional systems of personality with a well-validated factor structure (Sher et al., 2000), we use the Five-Factor Model (FFM) of personality, which is a widely used and dominant paradigm in personality psychology (Costa and McCrae, 1995; Ozer and Benet-Martinez, 2006; Terracciano et al., 2008). It covers the five major traits: openness to experience, conscientiousness, extraversion, agreeableness, and neuroticism (Costa and McCrae, 1995; Terracciano et al., 2008).

To our knowledge, this is the first study using a representative large-scale sample of German employees to investigate how personality traits are associated with CE. The only existing study that has examined the Big Five personality traits and a broad retrospective measure of CE (by combining certain prescription, non-prescription, and illegal drugs) with bivariate analyses is based on a student sample; the results are described below (Middendorff et al., 2012). Given this lack of research, our study can be informed by studies on the Big Five personality traits and other forms of substance use and misuse such as tobacco, alcohol, prescription stimulants, marihuana, etc.

Openness to experience can be described as a person's appreciation of new experiences and stimulation due to being imaginative, creative, unconventional, and emotionally as well as aesthetically sensitive (Caspi et al., 2005; John et al., 2008; Terracciano et al., 2008). It has been assumed that this willingness to engage in new experiences is a risk factor for the non-medical use of prescription drugs (Benotsch et al., 2013) and/or for detrimental substance use (Turiano et al., 2012). Specifically for CE, a greater openness to experiences has been presumed to promote CE-drug use due to higher eagerness to experiment (Middendorff et al., 2012). Several studies corroborate this assumption by showing that, for example, higher openness was positively associated with marijuana use (Terracciano et al., 2008) or illegal drug use in general (Turiano et al., 2012), opioid dependency (Kornør and Nordvik, 2007), cigarette smoking (Turiano et al., 2012), problem drinking (Turiano et al., 2012), a broader measure of substance-related risk-taking (defined as drinking, driving after drinking, smoking tobacco; Booth-Kewley and Vickers, 1994), substance-use disorder (Trull and Sher, 1994), and the non-medical use of prescription drugs (Benotsch et al., 2013). However, the only existing study of a set of different CE drugs found no effect (Middendorff et al., 2012).

Conscientiousness refers to an ability to control behavioral and cognitive impulses "that facilitates task- and goal-directed behavior, such as thinking before acting, delaying gratification, following norms and rules, and planning, organizing, and prioritizing tasks" (John et al., 2008, p. 138; cf. Caspi et al., 2005; Terracciano et al., 2008). It is seen as a protective factor against the non-medical use of prescription drugs (Benotsch et al., 2013) and the latter's specific form of CE-drug use (Middendorff et al., 2012), but also more generally against the detrimental use of other substances (Turiano et al., 2012). High levels of conscientiousness are assumed to play an important selfregulatory role and are associated with discipline and persistence and thus with disregarding the immediate gratification of health-damaging behaviors in order to obtain future, long-term outcomes (such as long-term health) "instead of " positive future, long-term health (Middendorff et al., 2012; Turiano et al., 2012; Benotsch et al., 2013). One argument is that since a reduced ability to engage in systematic and organized behavior has detrimental effects on learning, CE-drug use might be a means to compensate for these effects (Middendorff et al., 2012). Prior research has shown that procrastination, which can be seen as an example of this reduced ability, predicts a willingness to use CE drugs (Sattler et al., 2014). The only study on CE-drug use and conscientiousness thus far has also described a negative association between the two, namely that more conscientious students less were less likely to report using several drugs for purposes of CE (Middendorff et al., 2012). Furthermore, for a majority of respondents, CE-drug use violates social norms (e.g., fairness; Sattler et al., 2013b; Dubljevic et al., 2014; Schelle et al., ´ 2014; Wiegel et al., 2015; Sattler, in press) and since conscientious individuals tend to follow norms and rules, they might be less likely to use such drugs. Research on other types of substance use also found that increased conscientiousness is associated with a lower incidence of cigarette smoking (Terracciano et al., 2008; Turiano et al., 2012), of non-medical use of prescription drugs (Turiano et al., 2012; Benotsch et al., 2013), of use of illegal drugs such as marijuana, cocaine, and hallucinogens/lysergic acid diethylamide (LSD) (Terracciano et al., 2008; Turiano et al., 2012), of alcohol consumption (Malouff et al., 2007; Turiano et al., 2012), of substance use disorders (Trull and Sher, 1994), and specifically of opioid dependency (Kornør and Nordvik, 2007) as well as lower more general measures of the use of substances including cigarettes, alcohol, and recreational drugs (Atherton et al., 2014; cf., Lackner et al., 2013).

Extraversion reflects an energetic approach toward the world and can be understood as a person's tendency to be outgoing, expressive, active, energetic, assertive, cheerful, sociable, and in search of stimulation (Caspi et al., 2005; John et al., 2008; Terracciano et al., 2008). Some researchers have assumed neither an association between extraversion and CE-drug use specifically (Middendorff et al., 2012), nor with substance use in general (Turiano et al., 2012). However, several studies disprove this assumption. For example, it has been found that higher extraversion correlates with increased alcohol consumption (Turiano et al., 2012), more tolerant attitudes toward substance use (Francis, 1996), and more frequent use of substances including cigarettes, alcohol, and recreational drugs (Atherton et al., 2014). Yet, the association between extraversion and substance use may depend on the specific substance in question. Studies found that extraversion was higher in smokers as well as marijuana and cocaine/heroin users (Terracciano et al., 2008) but lower for opioid dependents (Kornør and Nordvik, 2007). A broad CE-measure, however, was uncorrelated with extraversion.

Agreeableness can be defined as a person's pro-social and communal orientation and includes a person's tendency to be altruistic, trustworthy, cooperative, considerate, empathic, polite, and modest (Caspi et al., 2005; John et al., 2008; Terracciano et al., 2008). While it has been assumed that agreeableness associates negatively with substance use (Booth-Kewley and Vickers, 1994; Turiano et al., 2012), for CE-drug use specifically it has been predicted that there would be no effect (Middendorff et al., 2012). This latter assumption has been supported by one study (Middendorff et al., 2012). For other substances, agreeableness seems to have a protecting effect, since more agreeable persons report lower marijuana use (Terracciano et al., 2008), alcohol consumption (Malouff et al., 2007; Turiano et al., 2012), nonmedical use of prescription drugs (Benotsch et al., 2013), polydrug abuse (Lackner et al., 2013), and alcohol dependency (Kornør and Nordvik, 2007).

Neuroticism includes feelings such as anxiety, nervousness, sadness, and depression and thus reflects a tendency to experience negative emotions (Caspi et al., 2005; John et al., 2008; Terracciano et al., 2008). Neuroticism is seen as a risk factor for CE-drug use (Middendorff et al., 2012) and more generally for the non-medical use of prescription drugs as well (Benotsch et al., 2013), but also for the use of other substances (Turiano et al., 2012). According to the self-medication hypothesis (Khantzian, 1997; West, 2005), individuals use drugs and may become dependent on them because they are vulnerable to stress, emotionally unstable, and thus may use CE to cope with emotional distress (Kornør and Nordvik, 2007; Benotsch et al., 2013). Contrary to these assumptions, neurotic individuals might also be more anxious about the potential side effects of CE-drug use, which might inhibit their use. However, several studies have corroborated that more neurotic individuals report higher use of a variety of substances, e.g., a broad CE-measure (Middendorff et al., 2012), alcohol consumption (Malouff et al., 2007; Turiano et al., 2012), cigarette smoking (Terracciano et al., 2008; Turiano et al., 2012), illegal drug use (Turiano et al., 2012) including cocaine and heroin (Benotsch et al., 2013), and prescription drug use especially anxiolytics and sedatives (Turiano et al., 2012; Benotsch et al., 2013); they are also more likely to report polydrug addiction (Lackner et al., 2013) and drug use disorder (Sher et al., 2000).

Due to scarce data on CE-drug use and the FFM and given the often inconsistent correlations between Big Five dimensions and many kinds of substance use and misuse from heterogeneous studies, there is a clear need for more research in this field (e.g., Booth-Kewley and Vickers, 1994; Francis, 1996; Malouff et al., 2007; Terracciano et al., 2008; Turiano et al., 2012; Benotsch et al., 2013; Lackner et al., 2013; Atherton et al., 2014).

By using data from a representative, large-scale random sample of German employees, this study aims at expanding our understanding of the prevalence of prior non-medical use of prescription drugs (a retrospective measure) and the willingness to use such drugs in the future (a prospective measure) with the subjective purpose of augmenting one's cognitive performance (by improving functions such as concentration, memory, or vigilance) as well as the association between the prevalence and willingness and the FFM traits. On a more general level, the study also adds to our understanding of the effect of personality traits on substance use: although mainly illicit drugs as well as substances such as alcohol and nicotine have been investigated in this regard, the non-medical use of prescription drugs has less frequently been the subject of research (Benotsch et al., 2013; N'Goran et al., 2014). Moreover, several studies on substance use and personality traits have investigated only one or a subset of traits of the FFM, while the present study investigates all five domains (Booth-Kewley and Vickers, 1994; Turiano et al., 2012; N'Goran et al., 2014).

#### METHODS

#### Research Design and Data Data

The data for this study are based on the first wave of the B3 Linked Employer-Employee Panel Survey (LEEP-B3) (Diewald et al., 2014). For the purpose at hand, we use the employeesurvey of the LEEP-B3 data, which were collected as computerassisted telephone interviews (CATI) in 2012–13 in Germany. Prior to the interviews selected participants were informed by a cover letter about the subject of the study, the voluntariness of their participation, their anonymity, and the confidentiality of all their answers. These issues were explained again during the first telephone contact. The underlying population comprises all employees in Germany who are subject to social security contributions, which applies to the majority of German employees—excluding only self-employed, marginally employed, apprentices, and civil servants. The net sample comprised 21,678 eligible respondents. The response rate was 29.77%, which leads to a total sample of 6454 (Diewald et al., 2014). Multivariate selectivity analyses comparing the sample to the underlying population using German registry data indicate that the LEEP-B3 data represent the underlying population rather well (Diewald et al., 2014). There is some limited selectivity, namely people who are German nationals and work in the "information and communication" sector participated in greater numbers, whereas people with lower levels of education and those working in very large organizations were less likely to participate.

#### Ethics Statement

In Germany, ethics approval for social science research is not required if research objectives do not investigate issues regulated by law (e.g., the German Medicine Act [Arzneimittelgesetz, AMG], the Medical Devices Act [Medizinproduktegesetz, MGP], the Stem Cell Research Act [Stammzellenforschungsgesetz, StFG], or the Medical Association's Professional Code of Conduct [Berufsordnung der Ärzte]). Since our study had no such objectives, approval was not required. Furthermore, paragraph 28 of the Data Protection Act of North Rhine Westphalia (Datenschutzgesetz Nordrhein-Westfalen, DSG NRW) explains that personal data have to be processed anonymously and that participants' consent is required only when the data are not used anonymously. Since data were collected in cooperation with the federal Institute for Employment Research (Institut für Arbeitsmarkt und Berufsforschung, IAB; Diewald et al., 2014), the study and all procedures were approved by the data security officer of the federal IAB and the Federal Ministry of Labor and Social Affairs (Bundesministerium für Arbeit und Soziales, BAMS). Prior to the interviews the selected participants were informed by a cover letter about the subject of the study. This letter explicitly informed the potential participants of the voluntariness of their participation, their anonymity, and the confidentiality of all their answers. During the first telephone contact, potential participants were again explicitly informed that their participation was voluntary, that all answers would be treated confidentially, and that the data would be anonymized. Thus, the act of participating in the study after receiving all relevant confidentiality information was taken to imply understanding and agreement.

#### Measures

#### Prior CE-Drug Use

We measured prior CE-drug use by asking: "Some people support their cognitive abilities with the help of prescription drugs, though there is no medical need (e.g., for increasing concentration, memory, or vigilance). Have you ever done that?" We provided the following response categories: "no, never" (0); "yes, within the last 30 days" (1); "yes, between the last 30 days and 6 months" (2); "yes, between the last 6 months and 1 year" (3); "yes, more than 1 year ago" (4) (cf. Sattler and Wiegel, 2013; Wiegel et al., 2015). Due to the low prevalence (see **Table 1**), a dichotomous variable was computed for our multivariate analysis, indicating no use (0) and prior use (1) (cf. Wiegel et al., 2015).

#### Willingness to Use CE Drugs

Given that CE-drug use can be described as a relatively new and potentially increasing phenomenon (e.g., Farah et al., 2004; Castaldi et al., 2012), we also assessed the respondents' willingness to use CE drugs, since this can be seen as one method for determining whether the postulated trend exists (Wiegel et al., 2015). Willingness measures are often used in research on the use of (licit and illicit) substances such as tobacco, alcohol, amphetamines, and marijuana, since they are used as proximal antecedents of future behavior (Gibbons et al., 1998a,b; Gerrard et al., 2006). However, an imperfect correlation between this measure and behavior may exist, since behavioral restrictions can change over time (cf. Grasmick and Bursik, 1990). But such measures are assumed to be less sensitive than behavioral measures and thus should result in fewer item-non responses or biased responses (e.g., Gibbons et al., 1998b). The CE-willingness measure was similar to the prior CE-drug use measure. Respondents were asked whether they could imagine using (or reusing) such prescription drugs for CE in the future (cf. Ponnet et al., 2015; Wiegel et al., 2015). Dichotomous response categories were "No, I would not do that under any circumstances" (0) and "Yes, I would do that under certain circumstances" (1) (cf. ZUMA, 1990).

#### Personality Traits

We used a short version of the Big Five Personality Traits Inventory (BFI-S) (Gerlitz and Schupp, 2005; Dehne and Schupp, 2007; Hahn et al., 2012) to assess the components of the FFM of personality (e.g., Costa and McCrae, 1995). Each of the five factors (openness to experience, conscientiousness, extraversion, agreeableness, and neuroticism) were measured by three items on five-point scales ranging from "I agree entirely" (1) to "I do not agree at all" (5). The items have been reverse-coded so that higher values indicate stronger agreement with the underlying factor (see Table S1). With regard to reliability, the BFI-S is a reasonable instrument for measuring the FFM in large, multi-purpose surveys (Lang et al., 2011). Similar to prior research (Dehne and Schupp, 2007), reliability analysis of the scales showed moderate internal consistencies: openness to experiences (artistic experiences, ideas, active imagination, α = 0.53), extraversion (talkative, sociable, reserved, α = 0.66), conscientiousness (efficient, thorough job, lazy, α = 0.55), agreeableness (forgiving, kind, rude, α = 0.45), and neuroticism (worried, nervous, relaxed, α = 0.54). However, since each item is supposed to measure a distinct facet within each dimension, the relatively low alpha values can be seen as an indication of the distinctness of the underlying facets (Rammstedt, 2010). We used explanatory factor analysis with varimax rotation to extract the five factors from the BFI-S (see Table S1). All items loaded substantially on the respective factor (openness with a mean factor loading of 0.68; extraversion with a mean factor loading of 0.76; conscientiousness with a mean factor loading of 0.69; agreeableness with a mean factor loading of 0.66; and neuroticism with a mean factor loading of 0.71) and showed low secondary loadings on other factors (mean secondary loading = 0.07).

#### Demographic Variables

Women were coded "0" and men "1" (see **Table 1** for this and other descriptive statistics). We also assessed gender (female = 0 and male = 1), age, education in years (each educational degree is assigned the average duration it takes to obtain), and personal gross monthly earnings in Euro.

#### Missing Values

The proportion of missing values is generally low (see **Table 1**). The highest proportion of missings can be found with earnings (4.93%, n = 318). Missing values were imputed using multivariate imputation by chained equations (MICE) (Azur et al., 2011; White et al., 2011) with 20 data sets. The following multivariate analyses are based on the imputed data sets, but all analyses have also been carried out using the unimputed data set (see Tables S2, S3).

#### TABLE 1 | Descriptive statistics with non-imputed data.

*Source: LEEP-B3, own computations.*

*aThis category includes 50 (0.78%) respondents indicating CE-drug use within the last 30 days, 24 (0.37%) respondents indicating such usage between the last 30 days and 6 months, 27 (0.42%) respondents indicating such usage between the last 6 months and 1 year and 90 respondents (1.40%) indicating that such usage was more than 1 year ago.*

#### Statistical Analysis

We used logistic regression models to test how the dependent variables covary with the independent variables. We report odds ratios (OR). ORs greater than 1 indicate positives effects of the independent variables on the respective dependent variable, while ORs lower than 1 indicate a negative effect, and ORs equal to 1 indicate no effect. The reported p-values are based on robust standard errors.

#### RESULTS

#### Prior CE-Drug Use

Our descriptive results (based on non-imputed data) show that approximately 97.04% (n = 6253) of the respondents report that they have never used prescription medication non-medically to support their cognitive abilities (see **Table 1**), while 2.96% (n = 191) reported such CE-drug use during their lifetime (see **Table 1**). In particular, 0.78% (n = 50) reported having used such drugs within the last 30 days, 0.37% (n = 24) between the last 30 days and 6 months, 0.42% (n = 27) between the last 6 months and 1 year, and 1.40% (n = 90) reported having used such drugs over a year ago. Our multivariate analysis (based on imputed data) focuses on the lifetime prevalence of CEdrug use only (see Methods section). Results show an OR of 0.774 (p < 0.001) in Model 1 in **Table 2**, which indicates a significant negative association between conscientiousness and prior CE-drug use. Thus, more conscientious respondents had a lower probability of prior CE-drug use. Moreover, we found a positive association between neuroticism and CE-drug use (p < 0.001). No significant associations were found for openness to experiences (p = 0.101), extraversion (p = 0.416), or agreeableness (p = 0.376). Prior use of CE drugs did not significantly vary with the socio-demographic controls gender (p = 0.865), age (p = 0.811), and earnings (p = 0.404)2 . Education, however, was found to have a negative association with prior CE-drug use (p = 0.049).

#### Willingness to Use CE Drugs

10.45% (n = 662, based on non-imputed data) of the respondents reported being willing to consume CE drugs in the future, while the remaining 89.55% (n = 5.670) indicated that they would never use such drugs (see **Table 1**). Multivariate analysis (based on imputed data) shows that the willingness to use CE drugs decreased if respondents showed stronger tendencies toward conscientiousness (p < 0.001) and it increased if respondents reported higher levels of neuroticism (p < 0.001) (see Model 2 in **Table 2**). Again, the effects for the domains openness to experience (p = 0.687), extraversion (p = 0.128), and agreeableness (p = 0.080) reached no conventional levels of significance. Males were less willing to use CE drugs in the future compared to females (p = 0.012). Age (p = 0.320), education (p = 0.414), and earnings (p = 0.848) had no significant effects on the willingness to use CE drugs3 . Respondents reporting the use of CE drugs in the past were much more willing to consume such drugs in the future compared to those who had never used such drugs (p < 0.001; **Table 2**, Model 3). Finally, we tested whether the effects of the five personality domains and the sociodemographic variables were conditional on prior use by adding interaction terms of these variables with prior use (see Table S3). Results show that no differential effects exist, i.e., the effects of the five personality domains and the socio-demographics on

2 In line with a developmental framework (e.g.,McLarnon et al., 2012), individuals in different stages of life might have different demands or propensities to use CE drugs (e.g., due to different peer exposure, risk preferences, or stressful periods). We therefore additionally tested quadratic and cubic functions of the age effect. Because no such effects were found, we do not show the results.

3Again, quadratic and cubic functions of the age effect were not significant.

TABLE 2 | Logistic regression models to assess associations of the BFI-S and socio-demographic controls with prior CE-drug use (Model 1) and the willingness to use CE drugs (Model 2 and 3) with imputed data (Number of imputations = 20, Number of observations = 6454).

*Source: LEEP-B3, own computations.*

*OR* = *Odds Ratios. CI* = *95% confidence intervals in parentheses (based on robust standard errors). Log pseudolikelihood and Pseudo R2 are averaged across imputed datasets.* \**p* < *0.05,* \*\**p* < *0.01,* \*\*\**p* < *0.001.*

the willingness to use CE drugs do not differ between users and non-users.

To facilitate the interpretation, the main results concerning the association between prior CE-drug use and the two personality traits of conscientiousness and neuroticism as well as the association between willingness to use CE drugs and these two traits are displayed in **Figure 1**. It shows predicted probabilities for both CE-measures using average marginal effects based on the multivariate models in **Table 2**. The predicted probabilities show that the effects associated with conscientiousness and neuroticism are rather large. The predicted difference between respondents with a low [defined by the mean (M) minus one standard deviation (SD)] and a high level of conscientiousness (M + 1 SD) is 39 percentage points (3.71 vs. 2.26%) in prior use and 31 percentage points regarding willingness to use (12.38 vs. 8.51%) (**Figures 1A,C**). As regards neuroticism, the predicted difference between respondents with a high level (M + 1 SD) and respondents with a low level (M – 1 SD) of this personality trait is 44 percentage points in prior use (3.76 vs. 2.10%) and 38 percentage points in willingness to use CE drugs (12.78 vs. 7.98%) (**Figures 1B,D**).

#### DISCUSSION

#### Summary and Interpretation of the Results Prevalence of CE-Drug Use and the Willingness to Take CE Drugs

While there is a fierce debate about whether CE-drug use is already a widespread phenomenon or whether it will be widespread in the future (Sahakian and Morein-Zamir, 2007; Greely et al., 2008; Ragan et al., 2013; Sattler et al., 2013a), limited research has been based on prevalence estimates derived from large-scale random samples beyond student populations (Hoebel et al., 2011; Mache et al., 2012; Sattler et al., 2013a; Fitz et al., 2014; Sattler, in press). We add to this research with data from more than **six** thousand employees in Germany randomly selected for this study (Diewald et al., 2014). We found a lifetime prevalence of nearly 3% for use of prescription drugs for supporting cognitive performance. This figure falls in the range of prevalence estimates of comparable prior studies (DAK Gesundheitsreport, 2009; Hoebel et al., 2011; Marschall et al., 2015) and shows that CE-drug use is already a fact, even if not a general practice, which opposes the current media hype about CE. Still, it has been estimated that more than half a million individuals in Germany have experience with CE-drug use (Kowalski, 2013); it can be presumed that a large number of these continue using (Sattler and Wiegel, 2013; Sattler et al., 2014; Wiegel et al., 2015), risking potential detrimental health effects often with no real effects or even detrimental effects. But the willingness to use such drugs in the future was more than three times greater than lifetime prevalence.  A similar difference between prior and potential future use has been found in a study of university teachers (Wiegel et al., 2015). Of course expressed willingness does not necessarily translates into actual behavior, for example due to changes in behavioral restrictions (cf. Grasmick and Bursik, 1990). However, discrepancies between willingness and use of CE drugs may also be explained by other factors. For example, potential users may not yet have experienced a pressing need to take such drugs, but would do so if the need were to occur, or they might not have had the opportunity (e.g., due to lack of access) to convert their interest into use (Singh et al., 2014; Wiegel et al., 2015). But drugs may become more available via the Internet and on the black market (Sahakian and Morein-Zamir, 2007). Potential users may also

for the willingness to use CE drugs (based on Model 2, Table 2).

want to wait until more effective and safer medication is available (DAK Gesundheitsreport, 2009; Franke et al., 2012; Wiegel et al., 2015).

#### Associations between Big Five Personality Traits and Prior CE-Drug Use and the Willingness to Engage in CE-Drug Use

Only relatively few studies (e.g.,Franke et al., 2012, 2013; Sattler and Wiegel, 2013; Wolff and Brand, 2013; Sattler et al., 2014; Wiegel et al., 2015; Maier et al., 2015) have responded to one of the first appeals for investigating how personality relates to CEdrug use (Quednow, 2010); in these the Big Five traits—which represent an important set of traits—have generally been ignored, with the exception of one study among students (Middendorff et al., 2012). By investigating the association between Big Five traits and prior CE-drug use as well as the willingness to use CE drugs in the future, we hope to add to our understanding of how a set of five major personality traits relates to such behavior. This also contributes to the often inconsistent findings between various kinds of substance use and misuse (including tobacco, alcohol, prescription stimulants, marihuana, etc.) and the FFM (e.g., Booth-Kewley and Vickers, 1994; Francis, 1996; Malouff et al., 2007; Terracciano et al., 2008; Turiano et al., 2012; Benotsch et al., 2013; Lackner et al., 2013; Atherton et al., 2014).

Similarly to a study of students using a broad retrospective measure of CE that combines certain prescription, nonprescription, and illegal drugs (Middendorff et al., 2012), we found that openness to experience was unrelated to both prior CE-drug use and the willingness measure. This, however, contradicts the assumption that the tendency to engage in new experiences and a greater eagerness to experiment produce a risk factor of higher involvement in substance use (Middendorff et al., 2012; Turiano et al., 2012; Benotsch et al., 2013). It also contradicts several findings regarding the use of multiple substances (e.g., illegal drug use, cigarette smoking, the non-medical use of prescription drugs), which found associations consistent with this assumption (e.g., Booth-Kewley and Vickers, 1994; Trull and Sher, 1994; Kornør and Nordvik, 2007; Terracciano et al., 2008; Turiano et al., 2012; Benotsch et al., 2013).

Respondents with higher levels of conscientiousness were less likely to report prior CE-drug use as well as a willingness to use CE drugs in the future. This is consistent with the supposition that conscientiousness serves as a protective factor against substance use (Middendorff et al., 2012; Turiano et al., 2012; Benotsch et al., 2013) and corroborates prior findings on a broad CE-drug measure (Middendorff et al., 2012) as well as many other substances such as alcohol consumption, cigarette smoking, prescription drug use, and illegal drug use (e.g., Trull and Sher, 1994; Kornør and Nordvik, 2007; Malouff et al., 2007; Terracciano et al., 2008; Turiano et al., 2012; Benotsch et al., 2013; Lackner et al., 2013; Atherton et al., 2014). This protective effect could be due to better self-regulation and persistence, which help to control impulses and delay the immediate gratifications of potentially health-damaging behaviors, while aiming for positive, long-term outcomes (such as long-term health) (Middendorff et al., 2012; Benotsch et al., 2013; Turiano et al., 2012). But also a greater ability to engage in systematic and organized behavior and consequently achieving better performance outcomes reduces the need to use CE drugs to compensate for the lack of such an ability (Middendorff et al., 2012). Furthermore, the increased tendency of conscientious individuals to follow norms might also decrease their likelihood to engage in behavior that many consider as morally objectionable (Sattler et al., 2013b; Dubljevic et al., 2014; ´ Schelle et al., 2014; Wiegel et al., 2015; Sattler, in press).

Our results also show no significant covariation between extraversion and our two CE-measures. This finding corroborates researchers' assumption that no such association should exist (Middendorff et al., 2012; Turiano et al., 2012) as well as the results of one study that found no association between CE-drug use and extraversion (Middendorff et al., 2012); at the same time some studies found that higher levels of extraversion can be associated with increased consumption of several substances (e.g., Kornør and Nordvik, 2007; Terracciano et al., 2008; Turiano et al., 2012; Atherton et al., 2014).

Agreeableness was neither significantly associated with our retrospective nor with the prospective CE-measure and thereby supports prior research on agreeableness and CE as well as the assumption that no such effect exists (Middendorff et al., 2012). For the use of other substances a negative association has been predicted (Booth-Kewley and Vickers, 1994; Turiano et al., 2012) and found (e.g., Kornør and Nordvik, 2007; Malouff et al., 2007; Terracciano et al., 2008; Turiano et al., 2012; Benotsch et al., 2013; Lackner et al., 2013), showing that agreeableness seems to have a protective effect.

It has also been shown that increased neuroticism leads to higher probabilities of prior CE-drug use and willingness to use CE drugs. Our results thus support the assumption that neuroticism is a risk factor for several kinds of substance use (Middendorff et al., 2012; Turiano et al., 2012; Benotsch et al., 2013).  One reason for these findings could be that neurotic individuals are less emotionally stable and more vulnerable to stress and therefore use these substances to cope with emotional distress (Kornør and Nordvik, 2007; Benotsch et al., 2013).

#### Associations Between Demographic Controls and Prior CE-Drug Use and Willingness to Engage in CE-Drug Use

With regard to the demographic controls, we found almost no significant differences regarding prior and potential future CE-drug use. While prior studies have shown mixed gender effects—generally finding no effect or a higher prevalence for males, but also that the purpose of use or the types of drugs used differ between sexes (e.g., McCabe et al., 2005; Rabiner et al., 2009, 2010; Weyandt et al., 2009; Ford and Ong, 2014; Singh et al., 2014; Ponnet et al., 2015; Wiegel et al., 2015) our study found that women showed a higher willingness to use CE drugs, which is consistent with another German largescale study (Hoebel et al., 2011). It has been assumed that such effects could indicate structural discrimination against women, namely that women need to work harder than men to rise in the hierarchy and at the same time often have twice or three times the amount of chores (work, children, and household) (Wiegel et al., 2015). This might increase the incentive for women to use such drugs as leverage in the job and to deal with their larger workload. Prior findings about the age-effect were indecisive (e.g., Maher, 2008; Terracciano et al., 2008; Benotsch et al., 2013; Ragan et al., 2013; Sattler and Wiegel, 2013; Sattler et al., 2013a; Ford and Ong, 2014; Singh et al., 2014; Wiegel et al., 2015), however, we found no age effect for both outcome variables. More years of education, however, were associated with a lower reporting of prior CE-drug use, which contradicts, for example, the study of Hoebel et al. (2011), which found no significant differences. One explanation could be that increased education is associated with greater knowledge about the limited efficiency of CE drugs. Additionally, for those with lower education, CE could be one means of compensating for lowered chances in the labor market or of dealing with potentially burdensome demands from their jobs. These assumptions have to be verified by future research. Respondents with potentially more monthly financial resources reported no elevated prior CE-drug use or willingness to do so in the future. In keeping with prior findings (Sattler and Wiegel, 2013; Sattler et al., 2014; Wiegel et al., 2015) and reasoning consistent with the Theory of Planned Behavior (Beck and Ajzen, 1991; Ouellette and Wood, 1998), we found a strong positive effect of prior CE-drug use on the willingness to consume such drugs in the future, indicating that many users have not only experimented once with these drugs but intend to continue using them (cf. Müller and Schumann, 2011). Users may have already made up their minds about their preferences or may be influenced by other factors such as a lack of self-control, sticking with their decisions out of habit and without further deliberation; they may have had positive experiences; or, in order to reduce potential cognitive dissonance, they may justify prior and continued drug consumption by ignoring negative information about CE-drug use or perceiving supporting information on a selective basis (Beck and Ajzen, 1991; Ouellette and Wood, 1998; Caviola et al., 2014; Wiegel et al., 2015).

# Limitations and Strengths of the Study and Directions for Future Research

The awareness of potential limitations is important when interpreting our results. We will describe these together with the strengths of our study as well as suggest directions for future research:

provide a full picture of the general population in Germany. However, our target population can be considered a large and important group in society. More research has been requested for our under-investigated target population (Greely et al., 2008; Ragan et al., 2013; Fitz et al., 2014; Schelle et al., 2014; Sattler, in press). This request is due to the repeated critique that most prior studies on factors influencing CE-drug use solely focused on students or other specific populations (Cutler, 2014; Ford and Ong, 2014; Wolff et al., 2014; Maier et al., 2015; Wiegel et al., 2015) and thus faced a limited generalizability.

4Over-reporting might occur in rare cases, but it is assumed to be less likely in our context since most people in prior studies voiced moral objections to using CE-drugs Sattler et al., 2013a,b; Schelle et al., 2014; Wiegel et al., 2015.

and it could be assumed that such effects are possible for CE-drug use as well. On the other hand, it has been argued that personality traits are relatively stable entities (Costa and McCrae, 1988; Soldz and Vaillant, 1999; Caspi et al., 2005; Terracciano et al., 2006; Turiano et al., 2012) and it has been assumed that they might not change rapidly through CE-drug use (Metzinger, 2012; Wulf et al., 2012), whereas some research has shown trait changes for other substances after as little as a few weeks or months (Tang et al., 2009). One study has shown that personality still had predictive power if there was a long time-lag between the assessment of personality and substance use (Turiano et al., 2012). But this study also found that personality changes affected substance use. These findings call for more longitudinal research to assess the covariation of personality and CE-drug use or substance use in general over time (Sher et al., 2000; Turiano et al., 2012; N'Goran et al., 2014). However, our results show that the associations found between the willingness measure and the personality traits was similar for nonusers and users. Thus, those who did not experience any potential personality changes from CE-drug use did not show a different willingness to use such drugs, which corroborates the effects on prior CE-drug use we found for personality traits. But still, our assessment of prior use did not cover the frequency, dosage, or duration of use, which can be seen as affecting substance-induced personality change. In addition, unmeasured confounder variables (such as genetic dispositions or social capital) could influence both personality and substance use, or personality could be influenced by these kinds of third variables, mediating their effect on substance use (Eysenck, 1999; Malouff et al., 2007; Schunck, 2014). Taken together and according to the reasoning of Malouff et al. (2007) on alcohol consumption, it is possible that (a) personality leads to CE-drug use, (b) CE-drug use leads to certain personality traits, (c) a third variable influences both, (d) personality mediates the effect of a third variable, or e) a combination of these effects is operating. Studies investigating these possibilities should also investigate variables that might influence the relationship between personality traits and CEdrug use, such as stress, social pressure, etc. (Francis, 1996; Benotsch et al., 2013). Data allowing such investigations do not currently exist.

This exploratory study investigated how prior and future CE-drug use and the Big Five traits are associated. To better understand its findings and those of earlier studies on the Big Five traits and various substances used for CE and other purposes, future research should put more emphasis on developing a coherent theoretical model. To test this model, more highly elaborated and fine-grained measures should be employed in order to challenge the robustness of our findings and obtain a more thorough comprehension of the relationship.

#### Conclusion

This large-scale study is based on a random sample of employees in Germany and shows that the use of prescription drugs to augment cognitive performance among healthy individuals is an empirical reality. However, this behavior is less widespread than had been anticipated by many scholars and media reports. But the significantly greater willingness to use CE drugs compared to the lifetime prevalence may be indicative of a possible increase in CE-drug use in the future. Still, the extent to which willingness to use CE drugs translates into actual behavior must be addressed in longitudinal studies. It remains to be discussed which threshold of willingness and prevalence justifies further prevention and regulation means. At the very least, a nonnegligible number of individuals already risks side-effects, longterm health consequences, and the involvement of the criminal justice system by using often non-efficient pharmaceutical agents. These individuals may also contribute to pressuring others to use such drugs, to increasing healthcare costs, and to other issues discussed in the ethics debate (e.g., CE-drug use in relation to the authenticity of users, fairness, or social inequality). This study increases our understanding of potential psychological factors that hamper or foster the use of CE drugs. We found that high levels of conscientiousness were associated with decreased retrospective/prospective consumption, while high levels of neuroticism increased it. Such insights about personality profiles could be used to inform the development of treatment approaches tailored to these profiles in order to minimize health problems (Booth-Kewley and Vickers, 1994; Terracciano et al., 2008; Conrod et al., 2011). Another approach would be to develop interventions to promote beneficial personality traits (e.g., increasing conscientiousness) and thereby support a positive change toward health-related behaviors in general (Magidson et al., 2014; Hudson and Fraley, 2015). However, less risky options for enhancing one's cognitive performance (such as sufficient sleep, seeking support, meditation, physical exercise) should be promoted for those who want or must enhance their performance (e.g., Bostrom and Sandberg, 2009; Dresler et al., 2013; Maier and Schaub, 2015; Wiegel et al., 2015).

# AUTHOR CONTRIBUTIONS

Wrote the Paper: SS, RS. Analyzed the data: RS.

# ACKNOWLEDGMENTS

This research was funded by the German Research Foundation (DFG; grant ID SFB882/01, B3, headed by Martin Diewald and Reinhard Schunck). SS's research was funded by a PostDoc Fellowship of the Fritz-Thyssen-Foundation and the Cologne Graduate School in Management, Economics and Social Sciences and through the support of a grant from the John Templeton Foundation, via The Enhancing Life Project. We thank Anna-Lena Peters as well as the two reviewers for critical and helpful comments and Cynthia Hall for editorial assistance. We acknowledge support for the Article Processing Charge by the German Research Foundation (DFG) and the Open Access Publication Fund of Bielefeld University.

#### SUPPLEMENTARY MATERIAL

The Supplementary Material for this article can be found online at: http://journal.frontiersin.org/article/10.3389/fpsyg. 2015.01971

# REFERENCES

correlates from a national survey. Addiction 99, 96–106. doi: 10.1111/j.1360- 0443.2005.00944.x

**Conflict of Interest Statement:** The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

The funders did not influence any interpretations or force the research team to produce biased results. The views expressed do not necessarily reflect the policies of the funder. The authors did not receive any research support from public or private actors in the pharmaceutical sector. The authors do not have any competing financial interests.

Copyright © 2016 Sattler and Schunck. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

# **Neuroenhancement and the strength model of self-control**

*Chris Englert 1 \* and Wanja Wolff 2*

*1 Department of Educational Psychology, Institute of Educational Science, University of Bern, Bern, Switzerland, 2 Department of Sport Psychology, University of Potsdam, Potsdam, Germany*

Neuroenhancement (NE), the use of substances as a means to enhance performance, has garnered considerable scientific attention of late. While ethical and epidemiological publications on the topic accumulate, there is a lack of theory-driven psychological research that aims at understanding psychological drivers of NE. In this perspective article we argue that self-control strength offers a promising theory-based approach to further understand and investigate NE behavior. Using the strength model of selfcontrol, we derive two theory-driven perspectives on NE-self-control research. First, we propose that individual differences in state/trait self-control strength differentially affect NE behavior based on one's individual experience of NE use. Building upon this, we outline promising research questions that (will) further elucidate our understanding of NE based on the strength model's propositions. Second, we discuss evidence indicating that popular NE substances (like Methylphenidate) may counteract imminent losses of selfcontrol strength. We outline how further research on NE's effects on the ego-depletion effect may further broaden our understanding of the strength model of self-control.

#### *Edited by:*

*Aaron Williamon, Royal College of Music, UK*

#### *Reviewed by:*

*Mats B. Küssner, Royal College of Music, UK Alexandra Cope, University of Leeds, UK*

#### *\*Correspondence:*

*Chris Englert, Department of Educational Psychology, Institute of Educational Science, University of Bern, Fabrikstrasse 8, 3012 Bern, Switzerland<EMAIL_ADDRESS>
#### *Specialty section:*

*This article was submitted to Performance Science, a section of the journal Frontiers in Psychology*

*Received: 13 July 2015 Accepted: 07 September 2015 Published: 24 September 2015*

#### *Citation:*

*Englert C and Wolff W (2015) Neuroenhancement and the strength model of self-control. Front. Psychol. 6:1425. doi: 10.3389/fpsyg.2015.01425* **Keywords: ego depletion, neuroenhancement, self-control, self-regulation**

# **Introduction**

A survey recently published in *Nature* revealed that one out of five respondents admitted having previously used substances as a means to enhance cognitive performance (Maher, 2008). The results of this survey fueled considerable research activity in the field of this so called *Neuroenhancement* (NE). We understand NE as a behavior that occurs within a defined means-end relation. This means a substance is being used as a means to enhance cognitive performance (Wolff and Brand, 2013; Wolff et al., 2014). *Drug Instrumentalization Theory* (DI-Theory) proposes that the means-end relationship that underlies such non-addictive drug use can be understood as a two-step process: "(1) the seeking and consumption of a psychoactive drug in order to change the present mental state into a previously learned mental state, which then allows for, (2) better performance of other, previously established behaviors and better goal achievement" (Mueller and Schumann, 2011). Understanding NE from the perspective of DI-Theory, an individual uses a substance with the aim of changing his or her current mental state (e.g., being tired and not concentrated) into a more desirable state (e.g., being alert and able to focus), which then allows for better performance. From a psychological perspective it is not important if the chosen substance is actually effective in enhancing performance. The assumed functionality attributed to a substance is seen as the driving force behind NE behavior (Wolff and Brand, 2013; Maier and Schaub, 2015). NE has therefore been defined as a healthy individuals' use of (psychoactive) substances under the assumption of these substances being functional means in order to enhance his or her already proficient cognitive capacities (Wolff et al., 2014).

Depending on what type of substances are subsumed under the NE concept by the extant research on NE, the reported prevalence rates vary to a great extent. Lifestyle drug NE (e.g., Red Bull) is the most prevalent with reported rates as high as 89% (Mache et al., 2012). Prescription drug NE (e.g., Ritalin) and illicit drug NE (e.g., Speed) are reported at much lower rates of well below 10% (e.g., McCabe et al., 2005, 2012; Teter et al., 2006). However, the real prevalence rates for prescription drugs and illicit substances NE may be much higher as social desirability is likely to bias the results: Using randomized response techniques, the 1 year prevalence rate of prescription drug NE has for example been found to be as high as 20% (Dietz et al., 2013). In our further discussion of NE, we follow the behavioral definition of NE and subsume all three variants (i.e., lifestyle drug, or soft; Maier and Schaub, 2015, prescription drug and illicit drug NE) under the NE concept.

The potential negative effects of lifestyle NE substances on health are mostly unknown to the general public (Rath, 2012). For instance, high levels of caffeine and sugar in lifestyle products can be associated with nervousness, headaches, and tachycardia (Clauson et al., 2008). Even caffeine related deaths have been reported (Clauson et al., 2008).

The high prevalence rates (e.g., McCabe et al., 2005, 2012; Teter et al., 2006) and the potential negative health consequences (e.g., Clauson et al., 2008; Rath, 2012) that are associated with the most frequently used drugs underline the necessity to get a better understanding of *why* individuals start and/or *continue* to neuroenhance. However, past research on NE has been mostly conducted rather unsystematically, as for instance psychological correlates of NE behavior have been collected mostly in an explorative manner as part of epidemiological approaches at the expense of theory-driven, experimental approaches (e.g., Weyandt et al., 2009; Mache et al., 2012). As an exception, one recent study applied the *strength model of self-control* (Baumeister, 2003; Baumeister et al., 2007) to predict first time NE behavior in an experimental setting (Wolff et al., 2013). While not explicitly focused on NE behavior, another experiment has investigated the effect of Methylphenidate (a substance commonly used for NE) on self-control strength (Sripada et al., 2014). Finally, a very recent field study investigated the relationship of trait self-control strength and doping intentions (Chan et al., 2015). Based on the few theory-driven approaches to NE, self-control strength (or selfcontrol demanding situations) seems to play an important role in NE behavior. We therefore think that the relationship between self-control and NE (and other forms of drug instrumentalization) warrants further investigation. We will explain our theoretical assumptions in more detail in the following sections.

# **The Strength Model of Self-control**

Self-control describes the ability to volitionally regulate ones' behavior or predominant response tendencies in order to achieve a desirable goal (e.g., Baumeister et al., 1994, 2007). For instance, while being on a diet one has to resist tempting but high caloric drinks or snacks in order to achieve the long term goal of losing weight (e.g., Kahan et al., 2003). However, self-control does not always work and the strength model of self-control offers a potential explanation for lapses in self-regulatory behavior (Baumeister et al., 1998). According to Baumeister et al. (1994) all self-control acts (e.g., emotion regulation, persistence) are empowered by one global metaphorical resource. There are interindividual differences in the capacity of this resource as some individuals are more adept in regulating themselves than others (i.e., trait self-control strength; e.g., Tangney et al., 2004). In general, this self-control strength has a limited capacity meaning that it can become temporarily depleted after having exerted selfcontrol strength, which is a state labeled *ego depletion* (i.e., state self-control strength; e.g., Muraven and Baumeister, 2000). In a state of ego depletion self-control deficits are more likely to occur as there is less self-control strength available to volitionally regulate ones' behavior (cf., Muraven and Baumeister, 2000). The effect of ego depletion is not domain-specific, meaning that previous acts of self-control in one domain (e.g., thought regulation) can have a negative carry-over effect on self-control performance in other, seemingly unrelated domains (e.g., emotion regulation; cf., Englert and Bertrams, 2013). Previous research has found a reliable effect of ego depletion on subsequent selfcontrol performance as Hagger et al. (2010) report a medium-tolarge effect of ego depletion on subsequent self-control in their meta-analysis.

Important for the present paper is the finding that under ego depletion individuals have a tendency to fall back onto their dominant behavioral tendencies (Govorun and Payne, 2006). For instance, restraint eaters are more likely to consume candy under ego depletion (Kahan et al., 2003; Hofmann et al., 2007) and in the same vein at-risk drinkers are more prone to relapses in a state of ego depletion (Ostafin et al., 2008).

# **Self-control and NE**

The strength model of self-control (e.g., Baumeister et al., 1994) allows for theoretically derived hypotheses regarding the self-control-NE relationship. Based on the strength models' predictions and the existing empirical evidence (e.g., Hagger et al., 2010) this relationship does not seem to be a trivial one. First, NE and self-control seem to be associated in a reciprocal fashion: Selfcontrol strength is associated with NE behavior (e.g., Wolff et al., 2013) and NE substances may also affect the availability of selfcontrol resources (Sripada et al., 2014). Second, they seem to be associated both on a macro and on a micro level: On a macro level, trait differences in self-control are associated with differences in functional (e.g., doping in sports) and non-functional (e.g., illicit drugs) substance abuse (Chan et al., 2015). On a micro level, temporary depletion of self-control resources affects decisions to consume substances as a function of one's history with such substance use behaviors (Wolff et al., 2013). In the following we will discuss these propositions in more detail.

#### **Self-control Resources Affect NE Behavior**

As previously mentioned, individuals have a tendency to follow their regular habits or behavioral tendencies in a state of ego depletion (Govorun and Payne, 2006). Govorun and Payne found out that participants in a state of ego depletion were more likely to rely on their automatic behavioral tendencies which in that case was the tendency to rely on their stereotypes (i.e., an automatically activated response tendency) in a decision task. On the contrary, participants with temporarily available self-control strength were more likely to suppress their stereotypes and to respond in a more desirable manner.

Based on these findings, ego-depletion should thus differentially affect NE behavior as a function of one's history with NE. If depleted, a regular user would be expected to neuroenhance as it is his or her dominant behavioral response tendency. This prediction is in line with the stereotypical image of an overwhelmed student who takes Ritalin® to meet an assignment deadline or a manager who—before an important meeting—takes cocaine to perform better. However, for firsttime NE users the predictions are reversed: If one has never used NE before, ego-depletion is predicted to elicit the dominant behavioral response which would then be to abstain from using a substance. This second prediction was investigated in a recent experiment (Wolff et al., 2013): Participants who had no history with NE were randomly assigned to a depletion or a nondepletion condition. After having worked on either a depleting or a non-depleting task, they were then informed that they would be asked to complete a cognitively demanding task after a short break. In this break they were given the opportunity to potentially enhance their performance with a caffeinated granulate. In line with the theoretical predictions, the depleted participants were actually significantly less likely to use the provided substance. So in this study, higher levels of state self-control strength were actually associated with a higher tendency to use NE to improve performance, indicating that higher levels of self-control strength were rather negative. This underlines the importance of self-control resources in the decision to neuroenhance for the first time and invites further research on the self-control-NE relationship. Most importantly, thus far the prediction that depletion leads to NE in habitual users has not been investigated and needs to be tested in future studies.

Chan et al. (2015) recently investigated how trait self-control strength is associated with athletes' attitudes toward doping and the intentions of using substances to improve athletic performance. The authors found out that athletes with lower levels of trait self-control strength were more likely to have a heightened attitude and intention toward doping in general, and a reduced intention, behavioral adherence, and awareness of doping avoidance. Even though this study did not test how temporary levels of self-control strength affect actual NE behavior it gives a first indication that trait self-control strength also plays an important role in the self-control-NE relationship that needs to be investigated in more detail.

#### **NE Substances Can Affect Self-control Resources**

In the previous section we discussed the complex relationship of ego depletion and the likelihood to use NE as a function of one's NE experience. However, NE use may also be an adaptive behavior as it may help to replenish depleted self-control strength more quickly. A recent study investigated the effects of a popular NE substance on state self-control strength (Sripada et al., 2014). Specifically, the study revealed that Methylphenidate was effective in preventing ego-depletion states in an experimental setting. Participants from a Methylphenidate condition that had performed a primary self-control task did not display the typical impaired performance in a second self-control task, while participants from a control condition that did not consume Methylphenidate showed the typical ego depletion effect. Even though Sripada et al. (2014) did not explicitly focus on NE, their study gives an indication that some NE substances may alleviate ego depletion effects. This is important, as alleviation of depleted self-control strength might be a mediating variable in the subjective effectiveness individuals assign to an NE substance. This alleviation potential may thus be one explanation for the popularity of certain NE substances. Further, this research shows that self-control and NE seem to be associated in a bidirectional way. However, thus far it has not been sufficiently investigated how NE and ego depletion are interrelated. More research is needed to investigate how and why NE substances can replenish one's self-control strength and how this potentially affects further NE behavior.

# **Discussion**

In the present paper, we argued for a theory-driven approach to investigate NE as thus far research in this field has been mostly conducted explorative. We identified the strength model of selfcontrol (Baumeister et al., 1998) as a promising candidate theory. Self-control and NE seem to be interrelated in a bidirectional manner: Self-control resources affect the initiation of NE behavior depending on one's personal NE experience (Wolff et al., 2013). Trait self-control strength is also related with one's attitude toward NE and the intentions of consuming NE (Chan et al., 2015). NE substances can also affect the availability of selfcontrol resources as certain substances may lead to a quicker revitalization of depleted self-control strength (Sripada et al., 2014). We reviewed research that can be seen as a first step to investigate both directions and outlined further research questions that would allow for theory-driven experimental research on NE.

The ethical verdict and policy implications on NE are still heavily debated (e.g., Farah et al., 2004; Greely et al., 2008; Forlini and Racine, 2009). The goal of this article was not to take a side in this debate as we do not recommend taking certain substances to replenish depleted self-control strength. We rather wanted to provide a theoretical backdrop for conducting psychological research on the initiation and the effects of NE. We are convinced that the complex relationship of NE and self-control warrants further investigation and will allow for a deeper understanding of this behavioral trend.

# **Author Contributions**

CE and WW substantially contributed to the writing of the manuscript. Both authors approve the final version of the manuscript. The authors agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

# **References**

**Conflict of Interest Statement:** The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

*Copyright © 2015 Englert and Wolff. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.*

fpsyg-07-00277 February 29, 2016 Time: 17:11 # 1

# Australian University Students' Coping Strategies and Use of Pharmaceutical Stimulants as Cognitive Enhancers

#### Charmaine Jensen1 \*, Cynthia Forlini2 , Brad Partridge1 and Wayne Hall1

1 Centre for Youth Substance Abuse Research, Royal Brisbane and Women's Hospital, Brisbane, QLD, Australia, 2 University of Queensland Centre for Clinical Research, Royal Brisbane and Women's Hospital Campus, The University of Queensland, Brisbane, QLD, Australia

Background: There are reports that some university students are using prescription stimulants for non-medical 'pharmaceutical cognitive enhancement (PCE)' to improve alertness, focus, memory, and mood in an attempt to manage the demands of study at university. Purported demand for PCEs in academic contexts have been based on incomplete understandings of student motivations, and often based on untested assumptions about the context within which stimulants are used. They may represent attempts to cope with biopsychosocial stressors in university life by offsetting students' inadequate coping responses, which in turn may affect their cognitive performance. This study aimed to identify (a) what strategies students adopted to cope with the stress of university life and, (b) to assess whether students who have used stimulants for PCE exhibit particular stress or coping patterns.

#### Edited by:

Ralf Brand, University Potsdam, Germany

#### Reviewed by:

Eleonora Concina, University of Padova, Italy Christiana Bagusat, University Medical Center of the Johannes Gutenberg University Mainz, Germany

> \*Correspondence: Charmaine Jensen<EMAIL_ADDRESS>
#### Specialty section:

This article was submitted to Performance Science, a section of the journal Frontiers in Psychology

Received: 19 November 2015 Accepted: 12 February 2016 Published: 01 March 2016

#### Citation:

Jensen C, Forlini C, Partridge B and Hall W (2016) Australian University Students' Coping Strategies and Use of Pharmaceutical Stimulants as Cognitive Enhancers. Front. Psychol. 7:277. doi: 10.3389/fpsyg.2016.00277 Methods: We interviewed 38 university students (with and without PCE experience) about their experience of managing student life, specifically their: educational values; study habits; achievement; stress management; getting assistance; competing activities and demands; health habits; and cognitive enhancement practices. All interview transcripts were coded into themes and analyzed.

Results: Our thematic analysis revealed that, generally, self-rated coping ability decreased as students' self-rated stress level increased. Students used emotionand problem-focused coping for the most part and adjustment-focused coping to a lesser extent. Avoidance, an emotion-focused coping strategy, was the most common, followed by problem-focused coping strategies, the use of cognition on enhancing substances, and planning and monitoring of workload. PCE users predominantly used avoidant emotion-focused coping strategies until they no longer mitigated the distress of approaching deadlines resulting in the use of prescription stimulants as a substancebased problem-focused coping strategy.

Conclusion: Our study suggests that students who choose coping responses that do not moderate stress where possible, may cause themselves additional distress and avoid learning more effective coping responses. Helping students to understand stress and coping, and develop realistic stress appraisal techniques, may assist students in general to maintain manageable distress levels and functioning. Furthermore, assisting students who may be inclined to use prescription stimulants for cognitive enhancement may reduce possible drug-related harms.

Keywords: prescription stimulants, cognitive enhancement, stress, coping, university students

# INTRODUCTION

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# Background

The non-medical use of prescription stimulants by healthy individuals to enhance alertness, focus, memory, mood and other cognitive functions (Hildt and Franke, 2013) has been dubbed 'pharmaceutical cognitive enhancement' (PCE) by some bioethicists. The stimulants commonly used for PCE include those used to treat Attention Deficit Hyperactivity Disorder, such as Ritalin, Concerta or Adderall, and wakefulness promoting agents used to treat Narcolepsy, for example Modafinil (Repantis, 2013). There is some evidence that some university students are using these stimulants for PCE purposes (Bavarian et al., 2013; Mazanov et al., 2013; Singh et al., 2014; Ram et al., 2015). The assumption commonly made in ethical analyses of this practice is that PCE helps students to manage the performance demands of university life.

Although the prevalence of PCE is reported to vary widely between countries and institutions, it is often discussed as if it were very common in all academic and professional environments (Maier and Schaub, 2015). Australian studies have found low rates of (lifetime) PCE use in the general population at 2.4% (Partridge et al., 2012) and university students with an average of 1.4 to 4.4% for 'study' and/or 'study only' purposes (Mazanov et al., 2013). Discussions of prevalence and purported demand for PCE in academic contexts have been based on incomplete understandings of student motivations, and often based on untested assumptions about the context within which stimulants are used (Lucke et al., 2011; Zohny, 2015).

Many of these assumptions focus on the academic aspects of university life, such as improving grades, increasing or maintaining academic competitiveness, improving the ability to learn, and self-medicating for difficulties studying (Greely et al., 2008; Rabiner et al., 2009; Lucke et al., 2013). Much of the research focusing on student use of stimulants has focused on identifying the prevalence of prescription stimulant use, assuming that all stimulant use is motivated by the desire to enhance cognitive performance (Greely et al., 2008). Motives for PCE use may also incorporate recreational and lifestyle purposes (Partridge, 2013). In one of the only studies to report on the context of student prescription stimulant use, Hildt and Franke (2013) argue that "if one takes the users' overall life situation into consideration, it seems that [they] perceive stimulants at least partly as beneficial for leading an 'active life' without being focused too much on academics" (Hildt et al., 2014). These findings call for a better understanding of the psychological and social factors that influence the use of prescription stimulants by university students for putative PCE purposes. Indeed, reasons for using stimulants as PCEs may encompass more than academic goals; they may also represent attempts to cope with biopsychosocial stressors in university life and to offset students' inadequate coping responses, which, in turn, may affect their cognitive performance.

# Coping Strategies

Stressors are situations or events that people perceive to be threatening to their physical, psychological, or social health, and may be acute or chronic. Coping refers to efforts to successfully navigate the challenges presented by stressors and alleviate associated distress (Snooks, 2009). Lazarus and Folkman identified that there are two common coping responses, problemfocused and emotion-focused coping (Lazarus and Folkman, 1984). Either or both of these coping responses represent a variety of coping strategies and can be applied in any given situation. The major difference between the two is whether or not the chosen coping response directly moderates the stressor. **Figure 1** briefly illustrates Lazarus and Folkman's theory of choosing a coping response (Lazarus and Folkman, 1984).

Proactive coping refers to actions that prevent or minimize exposure to known stressors (e.g., developing good sleep, exercise, and nutritional habits) (Snooks, 2009). If a stressor cannot be prevented or minimized with proactive coping habits (e.g., sleep is interrupted by worry over deadlines leaving the person tired and prone to stress), it is appraised to determine what type of response is needed to minimize distress. There are two stages to appraisal; primary and secondary appraisal. Primary appraisal asks "what does this potential stressor mean to me?" which determines if the stressor is benign. If it is not benign, the secondary appraisal involves asking "what can I do?"

As new information about the stressor is acknowledged (e.g., realizing that an assessment will take more time to complete than first thought), reappraisal evaluates alternative responses and their perceived effectiveness to manage distress. Reappraisal is often cyclical as new information about the stressor comes to light, thus a review of the stressor and the evaluation of potential coping strategies is repeated (Snooks, 2009).

Problem-focused coping aims to directly manage a stressor to reduce distress. This response is effective when an individual has the ability to moderate the stressor (e.g., by starting an assignment earlier to reduce distress as the deadline nears). Emotion-focused coping aims to cope with the emotions and feelings aroused by the stressor. This response may be chosen when it is not possible to change or moderate the stressor itself (e.g., seeking social support when you are disappointed with an assessment grade that cannot be changed). Avoidance is a common emotion-focused response that allows temporary respite from the stressor, but at the cost of prolonging or amplifying distress (Snooks, 2009; Taylor, 2012). It is important to note that both coping responses can be helpful in particular situations and that there is not one coping strategy that is better at managing distress across all situations (Snooks, 2009).

Previous studies investigating stress and coping strategies of college students generally found that students' perception of stress could predict their coping behavior (Kariv and Heiman, 2005), and that emotion-focused avoidant coping was more dominant than problem-focused coping. Some variables that mitigate the stress/coping relationship in previous studies are related to (1) gender, where masculinity is associated with problem-focused coping and femininity correlates with emotionfocused coping (Dyson and Renk, 2006; Brougham et al., 2009), fpsyg-07-00277 February 29, 2016 Time: 17:11 # 3

although studies vary on this finding; (2) age, particularly 1styear students (Kariv and Heiman, 2005; Dyson and Renk, 2006) where coping skills improve with practice and age (Snooks, 2009); and, (3) support, especially for those living away from family and friends during their studies (Dyson and Renk, 2006). Overall, improving coping behaviors, in particular problemfocused coping, appears to reduce depression symptomology (Steinhardt and Dolbier, 2008) and improve students' academic grades (MacCann et al., 2011).

A lack of effective coping experiences and skills may mean that younger people are not as effective at choosing the most helpful coping responses to the demands of student life. Young people may also be more inclined to choose coping strategies, such as the use of PCEs to help manage distress where other coping strategies are overlooked or ineffective. The findings discussed in this paper are a part of a broader qualitative study investigating factors in the academic, psychological and social context that influence students' interest in, and approaches to cognitive enhancement (including non-PCE methods).

#### Study Aims

Here we explore our interview data to understand how students coping strategies may be related to PCE use, and how cognitive enhancement behaviors may be explained by current coping theories. We analyzed perspectives of university students on the demands of student life with the aims of identifying (a) what strategies students adopted to cope with the stress of university life, and (b) to assess whether students who have used PCEs exhibit particular stress or coping patterns.

# MATERIALS AND METHODS

#### Participants and Recruitment

Ethics approval for this study was obtained from the University of Queensland in accordance with the National Statement on Ethical Conduct in Human Research (Australia). We recruited students aged 18–24 that were actively enrolled in university courses. Participants were recruited for a research study about students' study and health habits in several ways including: direct approach; posting flyers around campus noticeboards; the university's online student blackboard; and, snowballing. A second round of purposive advertising was carried out to diversify the sample and recruit additional PCE users by modifying the advertisements to include "study drugs". Approximately 250 students were screened in this second step to include more diversity in the use of caffeine, drugs, alcohol, and especially PCE use. Participants were compensated for their time with a \$20 Coles Myer gift card. Recruitment ceased once there were no new themes emerging from the interviews and data saturation was achieved.

# Procedure and Materials

Participants were first asked to complete a 12-item demographic survey about: sex; age; residential postcode; Australian residency; ethnicity; caring responsibilities; years at university; current degree; host university; study-load; grade point average of previous semester; and, hours of paid employment per week. All interviews were digitally recorded to MP3 files and independently transcribed. We removed any identifying information and replaced the participant's name with a number. Prior to commencement of the interview, participants were given an information sheet describing the study, what they would be required to do, and their rights as a participant. Interviews were conducted in 2013 by two members of the research team (CJ, CF).

The interview schedule focused on students' experience and attitudes toward studying and how they manage the demands of student life. Questions were open-ended so that participants were able to provide more detailed responses and then prompted by the interviewer if more information was required. The semistructured interview schedule consisted of several domains of interest: educational values ("Why is it important for you to get an education?"); study habits and achievement ("Can you describe what your study habits look like?" and "What do you think makes a successful student?"); stress management ("How do you manage stress when you are studying?"); getting assistance ("Where would you get support if you needed it?"); competing activities and responsibilities ("Do you find yourself compromising other areas of your life to study, or do you compromise your study to do other things?"); health habits ("What do you sleep patterns look like?"); and cognitive enhancement ("Do you consume other things that help you stay alerts, concentrate or study?").

#### Data Analysis

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Interview transcripts were analyzed using NVivo qualitative data analysis Software (QSR International Pty Ltd. Version 10, 2012). Each transcript was read by two investigators (CJ, CF) to identify errors in transcription and remove identifying information. An inductive approach to thematic analysis was used to code student responses. The initial analysis identified patterns in how students coped, including the use of PCEs, which emerged as a coping response. A more focused analysis was carried out to identify different patterns of coping between PCE users and non-users. **Table 1** displays the coding structure for coping-related strategies. 'Sources' represent the number of participants who referenced the respective theme, and 'references' denote how many times the collective sample of participants referenced a theme, that is, one source may reference a particular theme or content multiple times.

During the interview, students were asked about their level of perceived stress and their perceived coping ability. A 5-point Likert scale (1 = lowest and 5 = highest) was used and then graphed in scatterplot form (refer **Figure 2**). Due to multiple data points overlapping and reducing the visual plotting of data points, scores were 'jittered' (Marinsek, 2015) by adding a random number between the range of −0.1 to 0.1 to visually indicate multiple data points.

#### RESULTS

We recruited 38 full-time university students with a mean age of 20.95 years (ranging from 18 to 24 years), with more females (n = 22) than males. The majority were Australian residents (n = 28), with the balance of international students originating mainly from America or Asia. **Table 2** displays demographic information about the students in this sample.

The students interviewed displayed a negative relationship between their ability to cope with the demands of study and the level of stress that they reported experiencing. **Figure 2** displays

FIGURE 2 | Self-rated stress and coping levels. Red markers indicate repeat PCE users. Bold line denote trendline.

TABLE 2 | Sample demographics.

Parentheses denote standard deviation of scores.

students' self-rated stress in relation to their self-rated coping levels. Students, who rated their ability to cope with stress as high, reported less stress than those who reported low coping ability. There were five students who had previous experience using PCEs, of which four were repeat users. The four repeat PCE users rated higher stress levels and lower coping ability than average.

We identified different ways that students reported coping with the pressure of study and managing stress to explain the correlation in **Figure 2**. Each student might use a combination of coping strategies but generally followed a dominant strategy. Through the thematic analysis of the interview transcripts, we identified two major coping themes, and one minor coping theme (see **Table 1**). These were, respectively: emotionfocused coping; problem-focused coping; and, adjustmentfocused coping.

#### Emotion-Focused Coping

Emotion-focused coping strategies changed how students felt in the short-term when they experienced stress. These included: avoidance; seeking support; and switching activities.

#### Avoidant Strategies

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Avoidant strategies were the most common emotion-focused coping strategy. They involved the selection of activities that allowed students to avoid feelings of distress. The most common avoidant activities were: cleaning, eating, sleeping, checking/updating social media, and socializing.

Some students reported consistent use of avoidant behaviors. For example, "I probably sleep more because I'm trying to avoid it [study] then, or just trying to take my mind off it because it's the only time you don't really think about it" (11). Others avoided the task at hand with, "Anything so cleaning the house, surfing the internet, watching movies, going for a walk, cleaning the car, anything" (03).

Avoidant strategies provided short-term relief by allowing the student to avoid the unpleasant feelings associated with the study task. However, students did not necessarily enjoy the avoidant task, such as Student 27 who commented that: "It's like – the horrible thing is, I might normally enjoy watching YouTube videos or whatnot, but because I've got stress in the back of my mind, all enjoyment is kind of sucked out of it and it just becomes an avoidant activity", but this often does not reduce the stress afterward: "I could be playing browser based games, up to three in the morning. Just could be, just to forget about [what I have to do], yeah, and that obviously stresses me out".

Students often described avoidant strategies as unplanned. The duration of avoidant activities was often uncontrolled, potentially costing the student more time than anticipated. One student explained that: "Distractions probably go through the roof, just procrastination. Finding other things to do during the break but then the break seems to get longer and longer just because you're really sick of studying all day. . . . It's good to have the relaxation period but then because it goes on for so long you're pressured even more to study even harder and longer" (03).

Many students who used these strategies also reported that the stress of an approaching deadline motivated them to start study tasks, and that they probably need the distress to get started: "I'd just rather go out with my friends and do stuff. I knew it was bad and it stresses me out but I still did it. . . . Yeah I work better under pressure I think" (15).

The students who used PCEs predominantly used avoidant strategies and experienced additional stress when little progress had been made toward meeting a looming deadline. When this strategy no longer worked, Student 29 notes that, "I usually take it [Concerta] like before that [stress] happens just so I can start studying. But usually it just gets too close [to the deadline], even though I have that and I can study for hours it's still really stressful."

#### Social Support

Seeking social support was another emotion-focused coping strategy. Students sought support from friends, family, and peers about how they felt. For example, "Yeah if I'm having panic attacks and stuff mum will help just calm me down and put things in perspective, because it's just because I get overwhelmed and worried I won't get everything done. . . Yeah or someone to just talk at so I can put all my things in order and then realize I'm okay" (15).

Seeking support often had a positive outcome because it allayed some of the unpleasant feelings and provided new ways of seeing or approaching the task. Student 35 noted that, "I guess my family's pretty, like they're all pretty nice, and comforting so just being at home is quite good." Other types of social support allowed students to get back to the task in a more positive way, for example: "So I think talking helps . . . So I was really feeling bad afterward because he had to cope with me. But still, afterward you feel better because you talked with somebody about your day and what you still have to do. So that helped me, that somebody is there and says, well yeah, can I help you with that?" (08).

#### Switching Activities

Students often described switching activities if their study task was creating stress. This strategy uses a planned or controlled break away from the task to undertake activities that were not designed to progress the task directly but allowed the student to return to the task feeling less stressed. For example: "I find music really helps with stress, especially if it's – if there's not much I could really do in that situation, like if I just need to alleviate that anxiety I would just listen to music that I like for maybe 10 min and then I get better. Sometimes talking to a friend could work too or just – sometimes when it's really – sometimes you think you don't have time to do anything but then your brain just can't work. I find that during those times it's better to just remove yourself and say okay like take a break, take a walk somewhere and then come back to it" (06).

Switching activities differed from avoidant strategies because the intention was to relieve mental weariness rather than simply to avoid task-related stress. It was also a short-term strategy that often allowed the student to return to dealing with the stressor sooner. It was therefore more effective in addressing the task than other emotion-focused coping styles that did not moderate the stressor.

#### Problem-Focused Coping

Problem-focused coping strategies moderate the stressor directly, resulting in better long-term management of the stressor. Students described many ways in which they directly managed the stressors in their university lives.

#### Substance Use

Students were specifically asked if they used particular substances of any kind to help them study. The use of substances with the specific purpose as a study aid was the most commonly referenced problem-focused coping strategy across the sample. **Table 3** lists the substances that students were using to enhance their study performance during the academic semester the interview was conducted. This list does not reflect prior broader experience with substances for PCE or recreational purposes, which is represented in **Table 1**.

These putatively cognition-enhancing substances can be seen as a problem-focused coping strategy that allows students to moderate their distress by directly working on study goals. For instance, 'tiredness' was a common obstacle to working on academic tasks. Students reported using substances ". . . if I'm really tired and I have to do something" (11) or "if I have an fpsyg-07-00277 February 29, 2016 Time: 17:11 # 6

assignment due the next day, I'll buy an energy drink just to stay awake the whole night and make sure I don't fall asleep" (21).

Students were aware of potential cognitive enhancing properties of the substances they used and made a distinction between their use as a study aid and use for other purposes, such as enjoyment or long-term or general health benefits. For example, one participant acknowledged that they used energy drinks "To help pick me up, not for the taste. I know they're terrible for you, but sometimes you've got to do it, I find anyway" (34).

Some participants' use of cognitive enhancing substances and dietary supplements, although known for various long-term health benefits, were used specifically for cognition enhancing purposes: "I just take fish oil – just because of the – I know it's quoting from the neuroethics lecture about drugs that enhance cognition" (22).