Contextualising Experiences of Co-Occurring Mental Ill-Health and Substance Use Among Trans, Non-Binary, and Gender Diverse Young People: Implications for Tailored Harm Reduction Approaches.

Though significant research highlights higher rates of mental ill-health and substance use among trans, non-binary and gender diverse (henceforth 'trans') young people, little research has considered patterns, contextual characteristics, and correlates of co-occurring experiences of mental ill-health and substance use among trans young people. Using data from the Trans Pathways study, we used prevalence ratios and age- and gender-adjusted logistic regression models to examine prevalence and differences of co-occurring substance use (past six-month cigarette use, alcohol use, and other drug use) and contextual characteristics of substance use (past six-month solitary alcohol and/or drug use, substance use for coping) by mental ill-health (depression disorder, anxiety disorder, past 12-month self-harm thoughts and behaviours, suicidal thoughts, planning, and attempt/s). Age- and gender-adjusted models assessed associations between co-occurring depressive and anxiety disorders and recent cigarette, alcohol, and other drug use (six co-occurring items total) and 18 interpersonal stressors. Significantly increased odds of smoking or recent use of cannabis or sedatives was observed among trans young people reporting depressive disorder, anxiety disorder (aORs ranging 1.8-3.1). Trans young people who reported recent smoking or use of cannabis, inhalants, or sedatives, had 40% to 80% reduced odds of past 12-month self-harm thoughts, self-harm behaviours, suicidal thoughts, and suicide attempt/s (aORs ranging 0.2-0.6). On the other hand, solitary alcohol and/or other drug use and substance use for coping was significantly associated with increased odds of all mental ill-health outcomes. Issues with school, secure housing, and intimate partner abuse were the most robust correlates of co-occurring mental ill-health and substance use. Trans young people using substances, especially cigarettes, cannabis, and sedatives, often so do with co-occurring experiences of depression and anxiety though limited substance use in more 'social' contexts may confer benefits for preventing self-harm and suicide thoughts and behaviours. Continued research in partnership with trans young people is warranted to conceptualise more nuanced and precise conceptual parameters of trans-affirming substance use harm reduction approaches.