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Updated: Jan 18, 2026

Brain Morphology of Cannabis Users With or Without Psychosis: A Pilot MRI Study
Published on: August 18, 2020
Cannabis use and psychosis: a review of reviews
Alkomiet Hasan1, Rupert von Keller2, Chris Maria Friemel2
1Department of Psychiatry and Psychotherapy, Klinikum der Universität München, Nussbaumstrasse 7, 80336, Munich, Germany. Alkomiet.Hasan@med.uni-muenchen.de.
Abstract:
We conducted a systematic review of meta-analyses and systematic reviews to evaluate the impact of cannabis use on the onset and course of psychoses. Following a systematic literature search of five data bases (2005-2016) and consecutive structured evaluation, we were able to include 26 systematic reviews and meta-analyses. The methodological quality of the included publications were in the range of high and poor. The scientific literature indicates that psychotic illness arises more frequently in cannabis users compared to non-users, cannabis use is associated with a dose-dependent risk of developing psychotic illness, and cannabis users have an earlier onset of psychotic illness compared to non-users. Cannabis use was also associated with increased relapse rates, more hospitalizations and pronounced positive symptoms in psychotic patients. We make recommendations about the type of research that is required to better characterize the relationship between cannabis use and the development and outcomes of psychosis.
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