Hit the chronic… physical activity: are cannabis associated mental health changes in adolescents attenuated by...

High-frequency cannabis use in adolescents has been associated with adult mental illness. In contrast, physical activity has been demonstrated to benefit mental health status. The purpose of this study was to examine whether, within a 1-year prospective study design, changes in cannabis use frequency are associated with changes in mental health, and whether meeting physical activity guidelines moderates these associations.

COMPASS (2012-2021) is a hierarchical longitudinal health data survey from a rolling cohort of secondary school students across Canada; student-level mental health data linked from Years 5 (2016/17) and 6 (2017/18) were analysed (n = 3173, 12 schools). Multilevel conditional change regression models were used to assess associations between mental health scores change, cannabis use change and physical activity guideline adherence change after adjusting for covariates.

Adopting at least weekly cannabis use was associated with increases in depressive and anxiety symptoms and decreases in psychosocial well-being. Maintaining physical activity guidelines across both years improved psychosocial well-being regardless of cannabis use frequency, and offset increases in depressive symptoms among individuals who adopted high frequency cannabis use. Physical activity adherence had no apparent relationship with anxiety symptoms.

Regardless of the sequence of events, adopting high frequency cannabis use may be a useful behavioural marker of current or future emotional distress, and the need for interventions to address mental health. Physical activity adherence may be one approach to minimizing potential changes in mental health associated with increasing cannabis use.