Examining Daily Associations Between Mental Health Symptoms and Simultaneous Alcohol and Marijuana Use and Consequences Among Young Adults

Objective: The present study examined daily associations between mental health symptoms (i.e., depression and anxiety symptoms) and simultaneous alcohol and marijuana (SAM) use and use-related negative consequences among young adults. Method: Participants were a community sample of 409 young adults between the ages of 18-25 who drank alcohol at least three times in the past month and reported SAM use in the past month (M (age) = 21.6, 50.9% female). A baseline assessment included a measure of SAM use motives, after which participants completed five 14-day bursts reporting daily mental health symptoms and alcohol/marijuana use. Results: Daily mental health symptoms were not associated with SAM use likelihood. However, baseline SAM coping motives moderated the association between mental health symptoms and use such that young adults with stronger coping motives showed a stronger positive association between mental health symptoms and SAM use. Further, on SAM use days, reporting more mental health symptoms relative to one's average was associated with experiencing more use-related negative consequences, even after controlling for daily levels of alcohol and marijuana use (RR = 1.03, 95% CI = 1.01-1.05, p = .002). Conclusions: The association between daily mental health symptoms and SAM use depended on whether the young adults had coping motives for use. Daily fluctuations in mental health were associated with negative use-related consequences experienced on SAM use days regardless of motives. These findings highlight the potential importance of prevention and intervention strategies particularly on days when young adults are experiencing increased mental health symptoms. Public Health Significance Statement This study documented that mental health symptoms (i.e., symptoms of depression and anxiety) on a given day were associated with simultaneous alcohol and marijuana (SAM) use that day only for young adults with stronger baseline SAM coping motives. On SAM use days, greater mental health symptoms were associated with more negative consequences, regardless of motives for use. Elevated mental health symptoms on a given day are an indicator of substance use-related risk.