Genetic moderation of the effects of cannabis: Catechol-O-methyltransferase (COMT) affects the impact of {Delta}9-tetrahydrocannabinol (THC) on working memory performance but not on the occurrence of psychotic experiences

This study investigated the moderation of the impact of experimentally administered THC by COMT. Cognitive performance and psychotic experiences were studied in participants without a psychiatric diagnosis, using a between-subjects design (THC vs. placebo). The effect of COMT Val158Met genotype on the cognitive and psychotic effects of THC, administered intravenously in a double-blind, placebo-controlled manner to 78 participants who were vulnerable to paranoia, was examined. The results showed interactive effects of genotype and drug group (THC or placebo) on working memory, assayed using the Digit Span Backwards task. Specifically, THC impaired performance in COMT Val/Val, but not Met, carriers. In contrast, the effect of THC on psychotic experiences, measured using the Community Assessment of Psychic Experiences (CAPE) positive dimension, was unaffected by COMT genotype. This study is the largest to date examining the impact of COMT genotype on response to experimentally administered THC, and the first using a purely non-clinical cohort. The data suggest that COMT genotype moderates the cognitive, but not the psychotic, effects of acutely administered THC.

Source: Journal of Psychopharmacology - October 27, 2015 Category: Psychiatry Authors: Tunbridge, E. M., Dunn, G., Murray, R. M., Evans, N., Lister, R., Stumpenhorst, K., Harrison, P. J., Morrison, P. D., Freeman, D. Tags: Original Papers Source Type: research