Hempstead, NY: The use of cannabis doesn’t raise one’s risk of psychosis or other adverse health outcomes, even among adolescents who are at high risk for the disorder, according to longitudinal data published in the journal Psychiatry Research.
A team of researchers affiliated with Hofstra University in New York and with Stanford University in California assessed the relationship between cannabis use and health outcomes in a cohort of adolescents at clinical high risk for psychosis. Study participants were tracked for two years.
Investigators reported that those subjects who consumed cannabis were no more likely than non-users to become psychotic.
Authors concluded: [C]ontinuous cannabis use over 2-years of follow-up was not associated with an increased psychosis transition rate, and did not worsen clinical symptoms, functioning levels, or overall neurocognition … indicating that CHR [clinical high risk] youngsters are not negatively impacted by cannabis. … These findings should be confirmed in future clinical trials with larger samples of cannabis using individuals.”
The findings are similar to those published in April in the journal Psychiatry and Clinical Neurosciences. That study also failed to identify cannabis use as a risk factor for psychosis in clinically at-risk subjects. The study’s 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.”
By contrast, a recent Spanish study identified an increased risk of the development of a mental health disorder among youth admitted to treatment for cannabis use disorder.
Although the use of cannabis and other controlled substances tends to be more common among those with psychotic disorders, studies indicate that lifetime incidences of acute marijuana-induced psychosis are relatively rare among the general population. To date, the adoption of adult-use legalization laws in the United States has not been shown to be correlated with any increase in “overall rates of psychosis-related diagnoses or prescribed antipsychotics.”
Full text of the study, “Recreational cannabis use over time in individuals at clinical high risk for psychosis: Lack of associations with symptoms, neurocognitive, functioning, and treatment patterns,” appears in Psychiatry Research. Additional information is available from NORML.