Effects of cannabis use on outcomes of psychotic disorders: systematic review

It is unclear if research findings support clinical opinion that cannabis use leads to worse outcomes in people with psychosis, or whether this impression is confounded by other factors. To systematically review the evidence pertaining to whether cannabis affects outcome of psychotic disorders. We s...

Full description

Saved in:
Bibliographic Details
Published in:British journal of psychiatry 2008-11, Vol.193 (5), p.357-363
Main Authors: Zammit, Stanley, Moore, Theresa H. M., Lingford-Hughes, Anne, Barnes, Thomas R. E., Jones, Peter B., Burke, Margaret, Lewis, Glyn
Format: Article
Language:English
Subjects:
Alcohol
Cannabis
Clinical outcomes
Clinical research
Clinical Trials as Topic
Comorbidity
Drug abuse
Drug use
Experts
Extraction
Hallucinations
Health sciences
Humans
Longitudinal studies
Marijuana
Marijuana Abuse - psychology
Mental disorders
Mental health
Patient satisfaction
Pharmaceutical industry
Psychiatry
Psychoses
Psychosis
Psychotic Disorders - psychology
Quality assessment
Quality control
Recurrence
Relapse
Review Article
Schizophrenia
Severity of Illness Index
Substance abuse treatment
Systematic review
Violence
Young adults
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:It is unclear if research findings support clinical opinion that cannabis use leads to worse outcomes in people with psychosis, or whether this impression is confounded by other factors. To systematically review the evidence pertaining to whether cannabis affects outcome of psychotic disorders. We searched 10 relevant databases (to November 2006), reference lists of included studies and contacted experts. We included 13 longitudinal studies from 15,303 references. Data extraction and quality assessment were conducted independently and in duplicate. Cannabis use was consistently associated with increased relapse and non-adherence. Associations with other outcome measures were more disparate. Few studies adjusted for baseline illness severity, and most made no adjustment for alcohol, or other potentially important confounders. Adjusting for even a few confounders often resulted in substantial attenuation of results. Confidence that most associations reported were specifically due to cannabis is low. Despite clinical opinion, it remains important to establish whether cannabis is harmful, what outcomes are particularly susceptible, and how such effects are mediated. Studies to examine this further are eminently feasible.
ISSN:0007-1250
1472-1465
DOI:10.1192/bjp.bp.107.046375