We studied a mixed population of psychiatric outpatients and healthy volunteers in order to examine the gene-environment interaction effect of MAOA genotype and early trauma on the increased risk for self-reported levels of physical aggression during adulthood. We found that levels of physical aggression were significantly higher in men who had experienced traumatic events during the first 15 years of life and who carried the low expression allele (MAOA-L). When we repeated the analysis in the sub-sample of healthy volunteers, the results did not change. Our results are consistent with the majority of previous reports [14]–[17], [24] and point toward the MAOA genotype as a genetic factor that moderates the impact of early traumatic life events on the developmental pathway leading to later-life aggression.
