Tests for main and interaction effects of various allele combinations revealed that individuals who carried high function COMT and low-function DRD4 7R alleles (a combination expected to be associated with higher risk) did indeed show more lifetime substance abuse and, specifically, more cannabis abuse.
Our findings that COMT is associated with both NS personality traits and with the age of onset of heroin use helps to clarify the complex relationship between genetic and psychological factors in the development of substance abuse.
Some studies show that a catechol-O-methyltransferase (COMT) polymorphism affecting enzyme activity was associated with personality characteristics and diseases, such as novelty-seeking personality, substance abuse, and heroin addiction, whose features are similar to ADHD or are associated with ADHD.
Allelic variants at the catechol-O-methyltransferase (COMT) locus are candidates to contribute to genetic components of interindividual differences in vulnerability to substance abuse.