Health and Fitness

Marijuana Use Associated With ‘Superior’ Cognitive Performance In Schizophrenic Patients, Study Says

Toronto, Ontario–(ENEWSPF)–April 8, 2011.  Schizophrenic patients with a history of cannabis use demonstrate “superior neurocognitive performance” compared to non-users, according to the findings of a meta-analysis to be published in the journal Schizophrenia Research.

Investigators at the University of Toronto, Institute of Medical Sciences, performed a meta-analysis to determine the magnitude of the effect of cannabis consumption on cognition in subjects with schizophrenia. Eight studies met inclusion criteria, yielding a total sample of 942 subjects. Three hundred and fifty six of these participants were cannabis users with schizophrenia, and 586 were patients with no history of cannabis use. Neuropsychological tests were grouped into seven domains: general cognitive ability and intelligence; selective, sustained and divided attention; executive abilities; working memory and learning; retrieval and recognition; receptive and expressive language abilities and visuo-spatial and construction abilities.

Authors determined, “[R]elated statistics of differences in performance … all suggest superior cognitive functioning in cannabis-using patients as compared to non-using patient.”

Researchers stopped short of attributing subjects’ cannabis use to the improved outcome, noting that patients with superior cognitive skills may simply be more likely to acquire cannabis than subjects with lesser abilities.

They wrote: “Given that all studies that met inclusion criteria employed a cross-sectional methodological design, poses a challenge and limits the interpretation of our findings. That is, it is difficult to determine whether it is cannabis itself that triggers alterations in neuropsychological functioning or if drug-using patients represent a subset of the schizophrenia population who exhibit better neurocognitive performance.”

Authors concluded, “[C]annabis likely has modest … effects on neurocognitive function in schizophrenia. … Longitudinal designs studying the effects of cannabis abstinence or acute challenges are needed to parse the effects of cannabis per se on cognition in schizophrenia.”

Full text of the study, “The effects of cannabis use on neurocognition in schizophrenia: A meta-analysis,” will appear in Schizophrenia Research.