However, it doesn't appear that marijuana directly causes depression. It's likely that the genetic, environmental or other factors that trigger depression also lead to marijuana use. Some people with depression may use marijuana as a way to detach from their depressive symptoms. Heavy users may appear depressed as a result of the dulling effects of the drug on feelings and emotions. There also are links between marijuana and other mental health conditions. Marijuana use may trigger schizophrenia or detachment from reality (psychosis) in people who are at higher risk of psychosis.