Cannabis and depression risk

A total of 1146 individuals had depression (2.5%) during the 35 years of follow-up, and about 14% had used cannabis by age 18 to 20.

No association was found between frequency of cannabis use and risk of depression. Only subjects with the highest level of cannabis use had an increased crude hazard ratio for depression, but this association disappeared after adjustment for confounding factors.

In keeping with previous research, there was a strong graded association between cannabis use and schizoaffective disorder, even