Article

Cerebellar white-matter changes in Cannabis users with and without schizophrenia

School of Psychology, University of Wollongong, Australia.
Psychological Medicine (Impact Factor: 5.43). 04/2011; 41(11):2349-59. DOI: 10.1017/S003329171100050X
Source: PubMed

ABSTRACT The cerebellum is rich in cannabinoid receptors and implicated in the neuropathology of schizophrenia. Long-term cannabis use is associated with functional and structural brain changes similar to those evident in schizophrenia, yet its impact on cerebellar structure has not been determined. We examined cerebellar grey and white matter in cannabis users with and without schizophrenia.
Seventeen patients with schizophrenia and 31 healthy controls were recruited; 48% of the healthy group and 47% of the patients were long-term heavy cannabis users (mean 19.7 and 17.9 years near daily use respectively). Cerebellar measures were extracted from structural 3-T magnetic resonance imaging (MRI) scans using semi-automated methods, and examined using analysis of covariance (ANCOVA) and correlational analyses.
Cerebellar white-matter volume was reduced in cannabis users with and without schizophrenia compared to healthy non-users, by 29.7% and 23.9% respectively, and by 17.7% in patients without cannabis use. Healthy cannabis users did not differ in white-matter volume from either of the schizophrenia groups. There were no group differences in cerebellar grey matter or total volumes. Total cerebellar volume decreased as a function of duration of cannabis use in the healthy users. Psychotic symptoms and illness duration correlated with cerebellar measures differentially between patients with and without cannabis use.
Long-term heavy cannabis use in healthy individuals is associated with smaller cerebellar white-matter volume similar to that observed in schizophrenia. Reduced volumes were even more pronounced in patients with schizophrenia who use cannabis. Cannabis use may alter the course of brain maturational processes associated with schizophrenia.

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    • "10.1016/j.pharmthera.2014.11.009 Hulvershorn et al., 2011; Tham et al., 2011), and there is evidence that heavy cannabis use may speed up or worsen these changes amongst affected individuals (Medina et al., 2007b; Solowij et al., 2011b). However to date, there have been few studies that have prospectively examined associations between adolescent cannabis exposure, altered trajectories of brain development, and psychiatric or cognitive impairment in adulthood . "
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    • "In this study, we choose to use multiple rather than chronic Δ9-THC treatment to avoid negative emotional states (e.g., anxiety, depression, lack of motivation) [50], [51], and the reduction in the white and gray matter in the cerebellum often described in chronic cannabis users [52], [53]. Animal studies have reported long-lasting cognitive and memory deficits following chronic Δ9-THC exposure [54], [55], as well as neuronal death and reduced synaptic density of pyramidal neurons in the hippocampus [55], [56]. "
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