Patterns of marijuana use among psychiatry patients with depression and its impact on recovery

Background: Depression is associated with substance-related problems that worsen depression-related disability. Marijuana is frequently used by those with depression, yet whether its use contributes to significant barriers to recovery in this population has been understudied. Method: Participants were 307 psychiatry outpatients with depression; assessed at baseline, 3-, and 6-months on symptom (PHQ-9 and GAD-7), functioning (SF-12) and past-month marijuana use for a substance use intervention trial. Longitudinal growth models examined patterns and predictors of marijuana use and its impact on symptom and functional outcomes. Results: A considerable number of (40.7%; n=125) patients used marijuana within 30-days of baseline. Over 6 months, marijuana use decreased (B=-1.20, p<.001), but patterns varied by demographic and clinical characteristics. Depression (B=0.03, p<.001) symptoms contributed to increased marijuana use over the follow-up, and those aged 50+(B=0.44, p<.001) increased their marijuana use compared to the youngest age group. Marijuana use worsened depression (B=1.24, p<.001) and anxiety (B=0.80, p=.025) symptoms; marijuana use led to poorer mental health (B=-2.03, p=.010) functioning. Medical marijuana (26.8%; n=33) was associated with poorer physical health (B=-3.35, p=.044) functioning. Limitations: Participants were psychiatry outpatients, limiting generalizability. Conclusions: Marijuana use is common and associated with poor recovery among psychiatry outpatients with depression. Assessing for marijuana use and considering its use in light of its impact on depression recovery may help improve outcomes.