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Pot Use Associated With Enhanced Cognitive Performance In Schizophrenics

Thursday, 08 November 2007

Sydney, New South Wales: Cannabis use is associated with enhanced cognitive functioning in schizophrenic patients, according to clinical trial data published this month in the journal Schizophrenia Research.

Investigators at the University of Sydney assessed the impact of cannabis use on neuropsychological performance in patients diagnosed with schizophrenia or schizoaffective disorder. Sixty male schizophrenics and 17 healthy controls were recruited for the study. Among the schizophrenic group, 44 participants met the DSM-IV criteria for "lifetime cannabis abuse/dependence."

Investigators reported, "[W]ithin the schizophrenic group, a larger portion of participants with lifetime cannabis abuse/dependence demonstrated better performance than those without lifetime abuse/dependence. … Frequency and recency of cannabis use were also associated with better neuropsychological performance, predominantly in the domains of attention/processing speed and executive functions." (Executive functions are defined as a set of cognitive skills that are necessary to plan, monitor and execute a sequence of goal-directed complex actions.)

It has been estimated that cognitive dysfunctions are present in up to 80 percent of patients diagnosed with schizophrenia.

The Sydney study is the second clinical trial this year to report an association between cannabis use and improved cognitive performance in schizophrenic patients. In May, German researchers reported in the journal Progress in Neuro-Psychopharmacology & Biological Psychiatry that subjects who reported using marijuana prior to their first psychotic episode showed improved cognitive performance on certain tests compared to non-users.

A 2005 study by investigators at Manchester Metropolitan University in Britain previously reported that schizophrenic patients who consumed cannabis prior to disease onset possessed greater cognitive skills after ten years than did non-users.

For more information, please contact Paul Armentano, NORML Senior Policy Analyst, at: paul@norml.org. Full text of the study, "The neuropsychological correlates of cannabis use in schizophrenia: Lifetime abuse/dependence, frequency of use, and recency of use," appears in Schizophrenia Research.