Introduction and Aims. There is a lack of evidence regarding mental health disorder prevalence in people who use amphetamine-type stimulants (ATS). This study compares prevalence in Australian young adults who used ATS and young adults who had never used, and examines potential predictors. Design and Methods. Population-based sampling was used to recruit young adults who used ATS (n = 224) and young adults who had never used ATS (n = 125). Thirty-day prevalence of major depressive disorder (MDD), generalised anxiety disorder (GAD), panic disorder (PD), post-traumatic stress disorder (PTSD) and mania/hypomania were assessed using the Composite International Diagnostic Interview Short Scale. Adjusted prevalence ratios (APR) of mental disorders in people who used ATS and the comparison group were examined, and a prediction model was developed for people who used ATS. Results. We found higher prevalence of PD (APR 4.67, 95% confidence interval [CI] 1.14-19.07, P = 0.032) and PTSD (APR 1.68, 95% CI 1.10-2.55, P = 0.016) in people who used ATS, compared to the comparison group, adjusting for sociodemographic variables. Baseline methamphetamine use was positively associated with MDD (ARR 6.45, 95% CI 1.51-27.59, P = 0.012) and GAD (ARR 2.76, 95% CI 1.52-5.02, P = 0.001). Baseline ecstasy use was negatively associated with GAD (ARR 0.52, 95% CI 0.30-0.92, P = 0.025) and PD (ARR 0.15, 95% CI 0.05-0.48, P = 0.001). Discussion and Conclusion. PTSD and PD appear to be more common in young adults who use ATS. However, the relationship between ATS use and mental disorders is complex, with divergent patterns of association for ecstasy and methamphetamine use. Mental health screening in people using ATS may improve treatment outcomes. [Thoradeniya MR, Wessel EL, Pourmarzi D, Najman JM, Smirnov A. The prevalence of mental health disorders among young adults who use amphetamine-type stimulants, compared to young adults who do not.

Introduction Understanding reasons for choosing not to inject drugs, among those who have never injected before, may be helpful for reducing transitions to injecting drug use. This study examines opportunities to inject and reasons for never injecting in young adults who used stimulants. Methods Data are from a population‐based study of young adults who used ecstasy and methamphetamine (n = 313), recruited in Queensland, Australia in 2008/2009. At the follow‐up, participants who had never injected (n = 293) completed a 13‐item instrument on reasons for never injecting. We conducted a principal components analysis to identify types of reasons (scored 0–100) and multivariate regression to predict endorsement of these reasons. Results Approximately one‐in‐five of all participants ever had an opportunity to inject and there was no gender difference in the propensity to accept an opportunity. Four types of reasons, labelled risk perception, subjective effects, social environment and aversion, were identified. Male gender was associated with lower endorsement of risk perception (β = −7.94; 95% confidence interval [CI] −13.37, −2.51) and social environment (β = −7.35; 95% CI −13.15, −1.54). Having friends who injected was associated with lower endorsement of the social environment (β = −8.88; 95% CI −14.83, −2.94), and higher endorsement of aversion (β = 7.67; 95% CI 1.44, 13.89). Discussion and Conclusions Our findings suggest that injecting drug use opportunities are common among young adults engaged in recreational drug use, with males and females equally likely to accept an opportunity. A strong aversion to injecting and a hedonic preference for non‐injecting drug use may reduce the likelihood of accepting these opportunities.