Psychological Medicine



Original Article

The temporal dynamics of relationships between cannabis, psychosis and depression among young adults with psychotic disorders: findings from a 10-month prospective study


LOUISA DEGENHARDT a1c1, CHRIS TENNANT a2, STUART GILMOUR a1, DAVID SCHOFIELD a2, LOUISE NASH a2, WAYNE HALL a3 and DIANA McKAY a4
a1 National Drug and Alcohol Research Centre, University of New South Wales, Sydney, NSW, Australia
a2 University of Sydney, Psychological Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia
a3 School of Population Health, University of Queensland, St Lucia, QLD, Australia
a4 Private Practice, St Leonards, NSW, Australia

Article author query
degenhardt l   [PubMed][Google Scholar] 
tennant c   [PubMed][Google Scholar] 
gilmour s   [PubMed][Google Scholar] 
schofield d   [PubMed][Google Scholar] 
nash l   [PubMed][Google Scholar] 
hall w   [PubMed][Google Scholar] 
mckay d   [PubMed][Google Scholar] 

Abstract

Background. The aim was to examine the temporal relationships over 10 months between cannabis use and symptoms of psychosis and depression in people with schizophrenia and related disorders. The design was a prospective study of 101 patients with schizophrenia and related disorders who were assessed monthly over 10 months on medication compliance, cannabis and other drug use, symptoms of depression and symptoms of psychosis.

Method. Linear regression methods to assess relationships between cannabis use and symptoms of psychosis and depression while adjusting for serial dependence, medication compliance and other demographic and clinical variables.

Results. Cannabis use predicted a small but statistically significant increase in symptoms of psychosis, but not depression, after controlling for other differences between cannabis users and non-users. Symptoms of depression and psychosis did not predict cannabis use.

Conclusion. Continued cannabis use by persons with schizophrenia predicts a small increase in psychotic symptom severity but not vice versa.

(Published Online February 9 2007)


Correspondence:
c1 National Drug and Alcohol Research Centre, University of New South Wales, Sydney, NSW 2052, Australia. (Email: l.degenhardt@unsw.edu.au)


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