COMT and schizophrenia: This is in contrast to one previous small-scale acute laboratory study giving acute THC to patients with schizophrenia,26 and other work that suggested that COMT may mediate the psychotomimetic risk of cannabis3 but in agreement with subsequent larger studies that failed to replicate these findings.4, 27 There was a marginal effect of COMT on working memory performance at a low load when not intoxicated.