Dopaminergic Genetic Variation and Trait Impulsivity: The Role of COMT rs4680 in Mixed Behavioral and Substance Addictions.

Background: Impulsivity is a multidimensional trait associated with the development and maintenance of behavioral and substance addictions. Genetic polymorphisms, particularly within the dopaminergic system, are thought to modulate individual differences in impulsivity. The COMT rs4680 (Val158Met) polymorphism influences enzymatic activity of catechol-O-methyltransferase and may alter dopaminergic tone in the prefrontal cortex. This study investigated whether COMT rs4680 genotype interacts with addiction status (behavioral and substance addictions) to influence trait impulsivity. Methods: The study included 309 Polish men: 128 with mixed behavioral and substance addictions and 181 healthy controls. All participants completed the Barratt Impulsiveness Scale (BIS-11) and were genotyped for COMT rs4680. A two-way ANOVA was used to assess main and interaction effects of genotype and group on total and subscale BIS-11 scores. Results: Individuals with mixed addictions scored significantly higher on all BIS-11 subscales (p < 0.01). A significant interaction effect was observed for the Non-Planning (F2,303 = 4.40, p = 0.0131, η2 = 0.028) and Total BIS-11 scale (F2,303 = 5.77, p = 0.0035, η2 = 0.037), with the A/A genotype associated with increased impulsivity, especially among the clinical group. Conclusions: These findings support a gene-by-environment interaction in impulsivity, where COMT rs4680 Met/Met homozygotes may be more susceptible to heightened impulsivity in addiction contexts. The results highlight the potential utility of COMT genotyping in personalizing therapeutic strategies for impulse-related disorders such as addictive disorders. This study extends evidence on dopaminergic modulation of impulsivity to behavioral and substance addictions.