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Cannabis and psychosis: the impact of polydrug use

Shevlin, Mark, McElroy, Eoin, Murphy, Jamie, Hyland, Philip, Vallières, Frédérique, Elklit, Ask and Christoffersen, Mogens Nygaard (2017) Cannabis and psychosis: the impact of polydrug use. Drugs and Alcohol Today, 17 (3). pp. 186-194. ISSN 1745-9265

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While research has consistently identified an association between cannabis use and psychosis, few studies have examined this relationship in a polydrug context (i.e. combining cannabis with other illicit substances).

The present study sought to examine the association between recreational drug use (cannabis only v. polydrug) and psychotic disorders. Analysis was conducted on a large, representative survey of young Danish people aged 24 (N = 4,718). Participants completed self-report measures of lifetime drug use and this information was linked to the Danish psychiatric registry system.

Multivariate binary logistic regression analysis was used to examine the association between drug use (no drug use, cannabis only, cannabis and other drug) and ICD-10 psychotic disorders, while controlling for gender and parental history of psychosis. Compared with no drug use, the use of cannabis only did not increase the risk of psychosis while the odds ratio for cannabis and other drug were statistically significant.

Research limitations/implications
Psychosis risk may be associated with the cumulative effect of polydrug use.

Practical implications
Cannabis use may be a proxy for other drug use in research studies.

This study is innovative as it uses linked self-report and administrative data for a large sample. Administrative data was used to as an objective mental health status indicator.

Item Type: Article
Subjects: B Philosophy. Psychology. Religion > Psychology
Divisions: School of Business > Staff Research and Publications
Depositing User: Caoimhe Ní Mhaicín
Date Deposited: 10 Aug 2017 10:05
Last Modified: 14 May 2018 10:23

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