Reasons and subjective effects of cannabis use among people with psychotic disorders: a systematic review.
Cannabis use is a frequent problem among people with psychotic disorders that has been related to a worse prognosis. Understanding the reasons of cannabis use may help to develop comprehensive treatments and, as a result, improve the psychosis course.


METHODS
A systematic review of studies published in English and Spanish language from 1990 until March 2012 describing reasons for and subjective effects of cannabis use in patients with psychosis were reviewed. However, only those studies in which cannabis use was one of the three main substances studied were included.


RESULTS
Initially, 73 studies, of which 12 met the inclusion criteria, were identified. Most of the studies include heterogeneous patients, at different illness stages, and a few studies included a non-psychotic comparison group. The most common reasons for cannabis use were those related with social activities, mood disturbance, relaxation and getting high.


CONCLUSIONS
The most common reasons for cannabis use in patients with psychosis were related with social activities, mood disturbances, relaxation and getting high. However, a more homogeneous methodology need to be established, including different illness stages, to facilitate the interventions to reduce cannabis use in all phases of psychotic disorders development.
Institut de Neuropsiquiatria i Addiccions. Parc de Salut Mar. Barcelona.
Laura
L
Gómez Pérez
Institut de Neuropsiquiatria i Addiccions. Parc de Salut Mar. Barcelona. Unitat de Recerca en Neurociencia Cognitiva (URNC), Universitat Autonoma de Barcelona, Barcelona, Spain. Grup de Recerca en Neuroimatge (GREEN), Fundació IMIM, Spain. Programa Esquizofrenia Clínic, Hospital Clínic, Barcelona. Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM). Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM).
Anna Mané
AM
Santacana
Institut de Neuropsiquiatria i Addiccions. Parc de Salut Mar. Barcelona. Unitat de Recerca en Neurociencia Cognitiva (URNC), Universitat Autonoma de Barcelona, Barcelona, Spain. Grup de Recerca en Neuroimatge (GREEN), Fundació IMIM, Spain.
Daniel
D
Bergé Baquero
Institut de Neuropsiquiatria i Addiccions. Parc de Salut Mar. Barcelona. Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM).
Víctor
V
Pérez-Solá
D006801:Humans; D008385:Marijuana Smoking / Q000523:psychology*; D009042:Motivation; D011618:Psychotic Disorders / Q000523:psychology*