Physical Activity Moderates the Relationship Between Frequency of Past 90-Day Cannabis Use on Psychological Distress Among a National Sample of College Students

Physical activity (PA) positively impacts mental health by reducing psychological distress (PD), while cannabis use can increase PD. This study investigates the moderating effect of physical activity (PA) on the relationship between the frequency of past 90-day cannabis use (CU) and psychological distress (PD) among college students, using data from the American College Health Association’s National College Health Assessment III surveys (2019–2023). We explored the following research questions: (1) Does PA moderate the relationship between CU and PD? (2) How do different levels of PA influence PD and CU? The Kessler Psychological Distress Scale (K6) measured PD, and CU was categorized as never, once-monthly, and weekly-daily. Three PA measures (hours of moderate and vigorous activity, and days of strength training) were used in a Two-Step Cluster analysis to group participants by PA level. The study included 157,880 students from 127 universities, predominantly aged 18–29, biologically female, and non-Hispanic white. CU frequency was linked to increased PD, but higher PA levels were associated with lower PD. The interaction between PA and CU was significant, indicating PA moderates CU’s impact on PD. The study’s findings suggest that PA may serve as a protective factor against PD associated with CU. Public health strategies could incorporate PA as a harms reduction approach for cannabis users, particularly targeting college students who may be at high risk for PD. Future research should further explore the mechanisms underlying the moderating effect of physical activity and expand these findings to more diverse populations.