Journal article

Polydrug use, cannabis, and psychosis-like symptoms

Nicholas T Van Dam, Mitch Earleywine, Greg DiGiacomo



OBJECTIVE: To examine psychosis-like symptoms in users of legal and illicit drugs. METHODS: Schizotypal Personality Questionnaire (SPQ) scores were compared in groups of people with different exposure to cannabis, with the use of other drugs serving as a covariate. Supplemental analyses compared users of legal and illicit drugs with cannabis use as a covariate. RESULTS: Weekly (n = 111) and monthly (n = 136) cannabis users had higher scores on the SPQ than former (n = 143) and non-users (n = 81). The use of other drugs accounted for the links between cannabis and schizotypy. Lifetime use of psychomotor stimulant drugs plus ecstasy accounted for associations between cannabis and scores on the..

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Funding Acknowledgements

The authors thank Helene Verdoux, Gillinder Bedi, and two anonymous reviewers for comments on earlier drafts. All authors have contributed to the study and read the manuscript. Author M. E. declares involvement with a number of cannabis law reform groups. Authors N. V. D. and G. D. declare no conflict of interest. Data collection was supported by a grant from the Marijuana Policy Project. Marijuana Policy Project had no input on the design, analysis, written manuscript, or decision to submit for publication.