Adverse effect of catechol-O-methyltransferase (COMT) Val158Met met/met genotype in methamphetamine-related executive dysfunction.

•Executive dysfunction in methamphetamine users varies by COMT Val158Met genotype.•Methamphetamine effects on executive function are seen only in Met/Met carriers.•Val carriers have similar executive function irrespective of methamphetamine use.•Slower dopamine clearance conferred by Met is a liability in methamphetamine use.•COMT-controlled prefrontal dopamine bioavailability impacts methamphetamine injury.