More worrying news on how marijuana can drive severe mental illness: A systematic review published in Biomolecules in March found that “cannabinoids likely contribute to chronic psychotic events and schizophrenia, especially if taken during adolescence.” The review found that the odds ratio of developing psychosis-like events or schizophrenia was 2.88—with a twofold greater risk among teens.
The review analyzed 10 studies, all of which found that marijuana use was associated with an increased risk for schizophrenia or psychosis-like events. A shocking nine of these studies determined that the increased risk was statistically significant. The researchers noted that the “most intriguing result in our analysis is the large age effect,” pointing to the elevated risk among adolescents.
The researchers “speculate that cannabinoids have two major psychotic effects: acute psychotic sensations comparable to other hallucinogenic drugs and indicative of acute toxicity; and altered synaptic plasticity during adolescence.” These findings help explain the growing body of evidence linking marijuana use to severe mental illness.
The new data undermines a key prop of a deeply harmful belief not backed up by science: that the connection between schizophrenia and marijuana arises from sufferers using the drug to self-medicate. Wrong, notes Alison Knopf of Alcoholism & Drug Abuse Weekly. “The study does much to dispense with a ‘self-medication’ hypothesis—which would hold that people with schizophrenia use marijuana to control symptoms. This ‘chicken-and-egg’ conundrum may still persist, but the evidence indicates that it is the cannabis which came first in these cases.”