Risk of Acute Psychosis with Cannabis

Only a very small minority of individuals who use Cannabis will develop psychotic symptoms, however studies show that cannabis use is possibly the most modifiable environmental risk factor for schizophrenia.3 Genetic risk of a psychotic disorder may be suggested by the increased sensitivity to the effects of cannabis in individuals with a family history of schizophrenia[1,3] Positive schizophrenia-type symptoms from recent cannabis use were 15 times greater in unaffected siblings of patients with schizophrenia compared with controls. However, the genes that underpin this susceptibility remain unclear. An initial study suggested that a variant in the catechol-O-methyltransferase (COMT) gene (Val158Met) may mediate this sensitivity,1 but subsequent larger-scale studies failed to replicate this finding.2

Recently a new candidate for a gene - cannabis interaction has been identified in the AKT1 gene. The AKT1 gene codes for a protein that forms part of the dopamine receptor signalling cascade. Decreased AKT1 functionality may result in enhanced responses to dopamine receptor stimulation. THC has been found to acutely induce dopamine release in humans[4,5]

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