with a stimulant effect such as the snri antidepressants effexor (venlafaxine) or wellbutrin (bupropion) may seek out benzodiazepines or opioid narcotics to counter the anxiety and insomnia that such medications sometimes evoke. some studies show that nicotine administration can be effective for reducing motor side-effects of antipsychotics, with both bradykinesia (stiff muscles) and dyskinesia (involuntary movement) being prevented. alleviation of dysphoria theory the alleviation of dysphoria theory suggests that people with severe mental illness commonly have a negative self-image, which makes them vulnerable to using psychoactive substances to alleviate these feelings. despite the existence of a wide range of dysphoric feelings (anxiety, depression, boredom, and loneliness), the literature on self-reported reasons for use seems to lend support for the experience of these feelings being the primary motivator for alcohol use disorder and other drug misuse. multiple risk factor theory another theory is that there may be shared risk factors that can lead to both substance use and mental illness. mueser hypothesizes that these may include factors such as social isolation, poverty, lack of structured daily activity, lack of adult role responsibility, living in areas with high drug availability, and association with people who already misuse drugs. other evidence suggests that traumatic life events, such as sexual abuse, are associated with the development of psychiatric problems and substance use. the supersensitivity theory the supersensitivity theory proposes that certain individuals who have severe mental illness also have biological and psychological vulnerabilities, caused by genetic and early environmental life events. these interact with stressful life events and can result in either a psychiatric disorder or trigger a relapse into an existing illness. the theory states that although anti-psychotic medication can reduce the vulnerability, substance use may increase it, causing the individual to be more likely to experience negative consequences from using relatively small amounts of substances. these individuals, therefore, are "supersensitive" to the effects of certain substances, and individuals with psychotic illness such as schizophrenia may be less capable of sustaining moderate substance use over time without experiencing negative symptoms. although there are limitations in the research studies conducted in this area, namely that most have focused primarily on schizophrenia, this theory provides an explanation of why relatively low levels of substance misuse often result in negative consequences for individuals with severe mental illness. avoiding categorical diagnosis current nosological approach does not provide a framework for internal (sub-threshold symptoms) or external (comorbidity) heterogeneity of the different diagnostic categories. the prevailing "neo-kraepelinian" diagnostic system solely accounts for a categorical diagnosis, therefore not allowing for the possibility of dual diagnosis. there has been substantial criticism to the diagnostic and statistical manual of mental disorders (dsm-iv), due to problems of diagnostic overlap, lack of clear boundaries between normality and disease, a failure to take into account findings from novel research and the lack of diagnostic stability over time. history the traditional method for treating patients with dual diagnosis was a parallel treatment program. in this format, patients received mental health services from one clinician while addressing their substance use with a separate clinician. however, researchers found that parallel treatments were ineffective, suggesting a need to integrate the services addressing mental health with those addressing substance use. during the mid-1980s, a number of initiatives began to combine mental health and substance use disorder services in an attempt to meet this need. these programs worked to shift the method of treatment for substance use from a confrontational approach to a supportive one. they also introduced new methods to motivate clients and worked with them to develop long-term goals for their care. although the studies conducted by these initiatives did not have control groups, their results were promising and became the basis for more rigorous efforts to study and develop models of integrated treatment.