A recent study published in the journal Psychiatry Research shows no link between prolonged recreational cannabis use and psychosis, even in a cohort of adolescents deemed to be at high risk of developing the disorder.
Scientists affiliated with Hofstra University in New York and with Stanford University in California assessed participants for up to two years to determine if exposure to cannabis heightens the risk of psychosis.
The longitudinal study included adolescents under the age of 18, with a mean age of 16.4 years. 81% of the cohort were enrolled in school at the time of the study, 53% were male and 47% were female, 61.2% were white, 8.2% African American, 5.9% Asian, and 15.3% Hispanic.
The study’s authors wrote, “At baseline, there was an overall significant difference between the subgroups on age, with the ‘No Use’ subgroup being the youngest at 16.1 years old and the other two subgroups about a year older on average.”
“Continuous 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. Nevertheless, our findings suggest that continuously using cannabis may be associated with slightly elevated, albeit non-significant, attenuated positive symptom levels relative to non-users. This quite modest difference did not lead to significant increases in psychosis onset.”
The study also examined other neurological health factors in the cohort and found that “CHR [clinical high risk] youth who continuously used cannabis had higher neurocognition and social functioning over time, and decreased medication usage, relative to non-users. Surprisingly, clinical symptoms improved over time despite the medication decrease.”
Findings from this study concur with the results of a study previously covered by leafie which found no significant link between the development of psychotic disorders and cannabis use in a cohort of over 400 people mainly composed of individuals at high risk for psychosis.