Tuesday, October 12, 2010

Cannabis, Schizophrenia, Cognition, and Autoimmunity

When I was writing up the earlier piece last night I came across some searches from Norml, the rabidly pro marijuana organisation. The search page had the extract - schizophrenics have improved cognition if smoking pot. At the time I dismissed it but today I realised I was being silly, there is a very good neuroimmunological explanation for why cannabinoids can be helping schizophrenics.

In Pubmed I threw in the this search string - schizophrenia AND cannabis AND "working memory" - and it generated 15 hits. Here are some extracts ...

The Impact of Cannabis Use on Cognitive Functioning in Patients With Schizophrenia: A Meta-analysis of Existing Findings and New Data in a First-Episode Sample, Schizophrenia Bulletin, July 25, 2010

CANN = cannabis use
FEP = First episode patients

When directly compared, FEP + CANN patients performed better on tests of visual memory, working memory, and executive functioning. Patients with early onset cannabis use had less neuropsychological impairment than patients with later onset use. Together, these findings suggest that patients with schizophrenia or FEP with a history of cannabis use have superior neuropsychological functioning compared with nonusing patients. This association between better cognitive performance and cannabis use in schizophrenia may be driven by a subgroup of "neurocognitively less impaired" patients, who only developed psychosis after a relatively early initiation into cannabis use.
Contradictory cognitive capacities among substance-abusing patients with schizophrenia: a meta-analysis. Schizophrenia Res. Mar, 2008.

While consumption of alcohol was associated with a global cognitive scores similar to that of persons with Sz without an SUD and lower working memory capacities, preferential use of cannabis was instead associated with higher scores for problem solving and reasoning and visual memory. Age was inversely related to the size of the effects. It is concluded that previous mixed results obtained with cognitive evaluations of persons with Sz+SUD might reflect the heterogeneity of participants and that subgroups of patients might be defined on the basis of intermediate factors.
Given my earlier exploration of a possible autoimmune pathology being present in schizophrenia I decided for a simple search string - cannabinoids and autoimmunity. 7 hits, with this study, and this study, and this study, and this study, clearly pointing to endocannabinoid function being very important in limiting autoimmunity. Yes, I saw that coming. I won't go into the details of this, that would require another 3,000 word rant. There is a rather large body of research indicating that cannabinoids are highly neuroprotective. Now if you'll excuse me, I have to meet a man standing at the street corner ... .

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