Cannabis abuse increases the risk of later depressive symptoms (OR ~4), not vice versa.
Summary
Prospective ECA cohort study (total N=1.920; analysis subcohort without baseline depression n=849). Cannabis abuse at baseline → 4-fold increased risk of depressive symptoms at 14-year follow-up, after adjustment for age, sex, antisocial symptoms (OR approx. 4). Increased suicidal ideation and anhedonia. Reverse direction not significant (p>0.05): baseline depression did not predict cannabis abuse.
P
PopulationAdults from the Baltimore Epidemiologic Catchment Area (ECA) study, n=1.920 (subcohort without baseline depressive symptoms: n=849; subcohort without baseline cannabis abuse: n=1.837)
I
InterventionCannabis abuse (diagnosis according to Diagnostic Interview Schedule) at baseline 1980
C
ControlNo cannabis abuse at baseline
O
OutcomeIndividuals with cannabis abuse at baseline had a fourfold increased risk of depressive symptoms at follow-up (OR ~4,0, after adjustment for age, sex, antisocial symptoms and further covariates); depressive symptoms at baseline did not significantly predict cannabis abuse at follow-up
Confidence in the evidence
Very lowLowModerateHigh
Low
The second of four GRADE levels, the effect estimate is of limited reliability.
<h4>Objective</h4>This study sought to estimate the degree to which cannabis abuse is a risk factor for depressive symptoms rather than an effort to self-medicate depression.<h4>Method</h4>Participants (N=1,920) in the 1980 Baltimore Epidemiologic Catchment Area (ECA) study who were reassessed between 1994 and 1996 as part of a follow-up study provided the data. The analysis focused on two cohorts: those who reported no depressive symptoms at baseline (N=849) and those with no diagnosis of cannabis abuse at baseline (N=1,837). Symptoms of depression, cannabis abuse, and other psychiatric disorders were assessed with the Diagnostic Interview Schedule.<h4>Results</h4>In participants with no baseline depressive symptoms, those with a diagnosis of cannabis abuse at baseline were four times more likely than those with no cannabis abuse diagnosis to have depressive symptoms at the follow-up assessment, after adjusting for age, gender, antisocial symptoms, and other baseline covariates. In particular, these participants were more likely to have experienced suicidal ideation and anhedonia during the follow-up period. Among the participants who had no diagnosis of cannabis abuse at baseline, depressive symptoms at baseline failed to significantly predict cannabis abuse at the follow-up assessment.<h4>Conclusions</h4>Further research is needed to identify characteristics of individuals who abuse cannabis that account for their higher risk of depression to estimate the degree of impairment resulting from their depression.