Tensor-based morphometry of cannabis use on brain structure in individuals at elevated genetic risk of schizophrenia

• Published in: Psychological medicine 2013-10, Vol.43 (10), p.2087-2096
• Main Authors: Welch, K. A., Moorhead, T. W., McIntosh, A. M., Owens, D. G. C., Johnstone, E. C., Lawrie, S. M.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Adult and adolescent clinical studies; Anatomy & physiology; Biological and medical sciences; Brain; Cannabis; Cannabis - adverse effects; Cerebral Cortex - drug effects; Cerebral Cortex - pathology; Drug use; Familial factors; Female; Follow-Up Studies; Genetic engineering; Genetic Predisposition to Disease; Hippocampus - drug effects; Hippocampus - pathology; Humans; Magnetic resonance imaging; Magnetic Resonance Imaging - instrumentation; Magnetic Resonance Imaging - methods; Male; Marijuana; Medical sciences; Neuropsychology; Original Articles; Prefrontal Cortex - drug effects; Prefrontal Cortex - pathology; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Psychoses; Schizophrenia; Schizophrenia - genetics; Schizophrenia - pathology; Scotland; Young Adult
• ISSN: 0033-2917; 1469-8978
• DOI: 10.1017/S0033291712002668

Schizophrenia is associated with various brain structural abnormalities, including reduced volume of the hippocampi, prefrontal lobes and thalami. Cannabis use increases the risk of schizophrenia but reports of brain structural abnormalities in the cannabis-using population have not been consistent. We used automated image analysis to compare brain structural changes over time in people at elevated risk of schizophrenia for familial reasons who did and did not use cannabis. Magnetic resonance imaging (MRI) scans were obtained from subjects at high familial risk of schizophrenia at entry to the Edinburgh High Risk Study (EHRS) and approximately 2 years later. Differential grey matter (GM) loss in those exposed (n=23) and not exposed to cannabis (n=32) in the intervening period was compared using tensor-based morphometry (TBM). Cannabis exposure was associated with significantly greater loss of right anterior hippocampal (pcorrected=0.029, t=3.88) and left superior frontal lobe GM (pcorrected=0.026, t=4.68). The former finding remained significant even after the exclusion of individuals who had used other drugs during the inter-scan interval. Using an automated analysis of longitudinal data, we demonstrate an association between cannabis use and GM loss in currently well people at familial risk of developing schizophrenia. This observation may be important in understanding the link between cannabis exposure and the subsequent development of schizophrenia.