1. Introduction
habitual behaviors, habitual behaviors like substance, addictive behaviors, adverse health behavior measure, substance abuse
REGRESSION, SECONDARY
Vocational students are a risk group for problematic substance use and addictive behaviors. The study aim was to evaluate the effects of an app-based intervention on tobacco, e-cigarettes, alcohol, and cannabis use as well as gambling and digital media-related behaviors in the vocational school setting. A total of 277 classes with 4591 students (mean age 19.2 years) were consecutively recruited and randomized into an intervention (IG) or waitlist control group (CG). Students from IG classes received access to an app, which encouraged a voluntary commitment to reduce or completely abstain from the use of a specific substance, gambling, or media-related habit for 2 weeks. Substance use, gambling, and digital media use were assessed before and after the intervention in both groups with a mean of 7.7 weeks between assessments. Multi-level logistic regression models were used to test group differences. Intention-to-treat-results indicated that students from IG classes had a significantly larger improvement on a general adverse health behavior measure compared to CG (OR = 1.24, There is a substantial increase in substance use (tobacco, e-cigarettes, cannabis, alcohol) in the trajectory from adolescence to early adulthood [Apprentices and students in vocational training therefore represent an important target group for prevention and health promotion measures. In Germany, there are two settings for the implementation of those measures, either in companies or in vocational schools. While the organizational environment is particularly suitable for structural preventive measures, it is often difficult for companies to offer behavior-oriented measures. This especially applies to small and medium-sized enterprises (SMEs), which train 80% to 90% of apprentices in Germany [The majority of empirically evaluated school-based intervention programs is developed for regular school settings with younger target groups, while there has been a lack of comparable programs for vocational schools [A popular school-based prevention approach is the voluntary commitment to abstain from or reduce habitual behaviors like substance use. For example, one of the most widespread programs for the prevention of smoking in secondary schools in Germany is the smoke-free class competition “Be Smart—Don’t Start”. The core of the program is a joint voluntary commitment of school classes to stay smoke-free for a period of 6 months. It focuses on influencing social norms, promoting self-regulation, and addressing social influences by deploying cognitive-behavioral intervention techniques [To fill the gap in addiction prevention approaches for vocational students as a subpopulation with elevated risk for substance abuse and high media use, an app-based program has been developed, using a voluntary abstinence paradigm and addressing a wide selection of behaviors to incorporate a broad target group. The present study aimed to evaluate its effectiveness using a randomized design. It is expected that the intervention will increase the awareness of habitual behaviors (e.g., substance and digital media use) and will therefore lead to measurable reductions in these behaviors even after the end of the abstinence or reduction period. It is also expected that a temporary abstinence of a specific behavior will simultaneously affect other health behaviors and indicators of subjective well-being, even if the intervention does not directly address them.