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Comparative Study
. 2011 May;37(3):631-9.
doi: 10.1093/schbul/sbp126. Epub 2009 Nov 13.

Cannabis and first-episode psychosis: different long-term outcomes depending on continued or discontinued use

Ana González-Pinto  1 , Susana Alberich, Sara Barbeito, Miguel Gutierrez, Patricia Vega, Berta Ibáñez, Mahmoud Karim Haidar, Eduard Vieta, Celso Arango
Affiliations
Comparative Study

Cannabis and first-episode psychosis: different long-term outcomes depending on continued or discontinued use

Ana González-Pinto et al. Schizophr Bull. 2011 May.

Abstract

Objective: To examine the influence of cannabis use on long-term outcome in patients with a first psychotic episode, comparing patients who have never used cannabis with (a) those who used cannabis before the first episode but stopped using it during follow-up and (b) those who used cannabis both before the first episode and during follow-up.

Methods: Patients were studied following their first admission for psychosis. They were interviewed at years 1, 3, and 5. At follow-up after 8 years, functional outcome and alcohol and drug abuse were recorded. Patients were classified according to cannabis use: 25 had cannabis use before their first psychotic episode and continuous use during follow-up (CU), 27 had cannabis use before their first episode but stopped its use during follow-up (CUS), and 40 never used cannabis (NU).

Results: The 3 groups did not differ significantly in symptoms or functional outcome at baseline or during short-term follow-up. The CUS group exhibited better long-term functional outcome compared with the other 2 groups and had fewer negative symptoms than the CU group, after adjusting for potential confounders. For the CUS group, the effect size was 1.26 (95% confidence interval [CI]=0.65 to 1.86) for functional outcome and -0.72 (95% CI=-1.27 to -0.14) for negative symptoms. All patients experienced improvements in positive symptoms during long-term follow-up.

Conclusion: Cannabis has a deleterious effect, but stopping use after the first psychotic episode contributes to a clear improvement in outcome. The positive effects of stopping cannabis use can be seen more clearly in the long term.

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Figures

Fig. 1.
Fig. 1.
Global Assessment of Functioning (GAF) Outcome by Cannabis Use Group.
Fig. 2.
Fig. 2.
Positive and Negative Symptoms Scale (PANSS) Positive Symptoms Outcome by Cannabis Use Group.
Fig. 3.
Fig. 3.
Positive and Negative Symptoms Scale (PANSS) Negative Symptoms Outcome by Cannabis Use Group.
See this image and copyright information in PMC

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