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Does Cannabis Use Cause Psychosis?

London, United Kingdom: A history of cannabis use is not associated with an increased risk of developing psychosis, even among those predisposed to the disorder, according to data published in the journal Psychiatry and Clinical Neurosciences.

A team of investigators from Australia, Europe, and the United Kingdom examined the association between cannabis use and incidences of psychotic disorders in clinically at-risk subjects. Researchers assessed subjects at baseline and then followed them for a period of two years.

They reported: “There was no significant association between any measure of cannabis use at baseline and either transition to psychosis, the persistence of symptoms, or functional outcomes.”

Authors concluded,  “Our primary hypothesis was that cannabis use in CHR [clinically high risk] subjects would be associated with an increased rate of later transition to psychosis. However, there was no significant association with any measure of cannabis use. … These findings are not consistent with epidemiological data linking cannabis use to an increased risk of developing psychosis.”

Although the use of cannabis and other controlled substances tends to be more common among those with psychotic illnesses, studies indicate that lifetime incidences of acute marijuana-induced psychosis are relatively rare among the general population.

Data published last year in the New Zealand Medical Journal reported that those with a history of cannabis consumption do not typically exhibit more severe symptoms of psychosis than do those with no history of regular use.

Full text of the study, “Influence of cannabis use on incidence of psychosis in people at clinical high risk,” appears in Psychiatry and Clinical Neurosciences.

Source: NORMLmake a donation