In Psychiatric Times, Robin Murray discusses a number of studies and what the balance of evidence seems to be saying about the relationship between cannabis use and increased risk of short or long-term psychotic reactions in some people.
Murray argues that bad reactions seem most likely to emerge in a small percentage of people who start smoking marijuana at a younger age, smoke high potency marijuana, or smoke daily. However, Murray adds, since so many people smoke marijuana, psychotic reactions could be occurring in millions of people globally.
“In many ways, cannabis is similar to alcohol; most of those who use it do so moderately, enjoy it, and suffer few if any adverse effects,” begins Murray. “However, in a minority of heavy users, problems develop. Given the likelihood that cannabis will become more available, it is important to establish any harms its use may cause so clinicians can identify and treat these. The main psychological harms that have been reported are dependence, cognitive impairment, and psychosis.”
Marijuana and Madness: Clinical Implications of Increased Availability and Potency (Psychiatric Times, April 30, 2015. Full text with free registration.)