The association between cannabis use and mood disorders: A longitudinal study

Area of Science:

• Psychiatry
• Epidemiology
• Addiction Medicine

Background:

• The relationship between cannabis use and mood disorders like major depressive disorder (MDD) and bipolar disorder (BPD) is complex and debated.
• Existing research on causality is conflicting, necessitating further investigation.

Purpose of the Study:

• To prospectively examine the association between cannabis use and the incidence of MDD and BPD.
• To explore whether baseline mood disorders predict future cannabis use initiation.

Main Methods:

• Utilized data from waves 1 and 2 of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC).
• Defined MDD and BPD based on full diagnostic criteria met in the 12 months prior to follow-up.
• Identified cannabis use initiation as any use by previous abstainers between baseline and follow-up.

Main Results:

• Cannabis use did not show a significant association with the increased incidence of MDD.
• Weekly to almost daily cannabis use was linked to a higher incidence of BPD, though daily use was not.
• Individuals with baseline MDD were more likely to initiate cannabis use, while baseline BPD did not predict initiation in adjusted models.

Conclusions:

• Findings do not support a longitudinal association between cannabis use and the incidence of MDD.
• The association between cannabis use and BPD incidence remains conflicting and warrants further research.
• Baseline MDD may be a predictor for initiating cannabis use, with potential clinical and social implications.