Marijuana Use Associated With Worse Depression Outcomes

Colorado rejects medical marijuana for PTSD treatment
Colorado rejects medical marijuana for PTSD treatment
Results indicate a need for providers to ask depressed patients about their marijuana use.

In a study of outpatients with depression, researchers found that marijuana use was common and that its use was associated with poor recovery.

Amber L. Bahorik, PhD, from the UCSF Weill Institute for Neurosciences at the University of California-San Francisco and colleagues recruited 307 outpatients with depression from the Kaiser Permanente Southern Alameda Center department of psychiatry in Union City and Fremont, California.

The researchers assessed the patients at baseline, 3 months, and 6 months on symptoms (Patient Health Questionnaire [PHQ-9] and Generalized Anxiety Disorder scale [GAD-7]), functioning (SF-12), and past-month marijuana use. Longitudinal growth models were used to examine patterns and predictors of marijuana use, and to assess its impact on symptom and functional outcomes.

The researchers found that “a considerable number” of patients (40.7%; n=125) 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. Marijuana use was significantly increased in patients age 50 and older over 6-months compared with the youngest age group (B = 0.44, P <.001), although patients age 50 and older were less likely to use marijuana at baseline.

Six-month recovery trajectories showed that marijuana use was significantly associated with worse recovery for depression symptoms (B = 1.24 [95% CI=0.466-2.015], P = <.001) and anxiety symptoms (B = 0.80 [95% CI = 0.101-1.509], P =.025), ans mental health functioning (B = −2.03 [95% CI = −3.587− 0.472], P =.010) compared with patients not using marijuana.

No significant differences in symptoms or mental health functioning outcomes (P‘s >.05) were found between patients who reported recreational or medicinal marijuana use, although patients who reported medicinal marijuana use had significantly poorer physical health functioning compared with patients who reported recreational use (B = −3.35 [95% CI = −6.603- −0.096], P =.044).

“Our results warrant replication and indicate a need for providers to ask depressed patients about their marijuana use, to inform those using marijuana of its potential risks and determine treatment needs,” the investigators wrote. “Education efforts about the adverse impact marijuana use can have on depression are needed, with a focus on subgroups (ie, young people and older adults, high depression severity patients) at risk for poor outcome.”


  • Patients were participants in a trial of alcohol and drug use and had a PHQ-9 depression score of ≥5, limiting generalizability
  • Participants were using substances other than marijuana, limiting the researchers’ ability to draw firm conclusions
  • Self-reporting is subject to recall bias
  • Models were unadjusted for patients’ premorbid functioning/marijuana use, which could have had an impact on the results
  • Substance use variables were separated due to low frequency, reducing statistical power
  • The researchers do not know how marijuana was ingested
  • Longitudinal analyses are limited to a 6-month follow-up, suggesting further research is needed over longer periods of time

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    Bahorik AL, Leibowitz A, Sterling SA, et al. Patterns of marijuana use among psychiatry patients with depression and its impact on recovery. J Affect Disord. 2017;312:168-171. doi:10.1016/j.jad.2017.02.016