Dopamine D3 receptor gene polymorphism and violent behavior: relation to impulsiveness and ADHD-related psychopathology.

Several lines of evidence indicate that dopaminergic neurotransmission is involved in the regulation of impulsive aggression and violence and that genetically determined variability in dopaminergic gene expression modifies complex traits including that of impulsivity and aggression. In this study we report an association of the dopamine D3 receptor (DRD3) polymorphism with impulsiveness according to Eysenck's EIQ and scores on the German short version of the Wender Utah Rating Scale (WURS-k), which we used for the assessment of a history of ADHD-related symptoms. This association was detected in a group of violent offenders, but not in non-violent individuals. Highest scores of EIQ impulsiveness and of the WURS-k were found in heterozygous violent individuals, while homozygotes showed significant lower rating scores, suggesting an heterosis effect. The results of our study suggest that variations of the DRD3 gene are likely involved in the regulation of impulsivity and some psychopathological aspects of ADHD related to violent behavior.