Objectives. Impulsiveness as a heritable characteristic being both a symptom of many mental disorders and a personality trait of healthy individuals meets the criteria for an endophenotype. The article presents a review of the research literature on genetic and environmental determinants of impulsivity.
Background. Genetic factors are responsible for about 45% of variation in impulsiveness levels in twins, while the remaining variation is accounted for by demographic and psychosocial factors including age, education and economic situation that modify and shape the level of impulsiveness since early childhood. Genetic research findings to date indicate that functional polymorphisms in the dopaminergic and serotonergic system genes are crucial to the regulation of impulsivity. Genetic variants responsible for high activity of D2 and D4 receptors as well as low activity of the dopamine transporter and COMT have been found to be associated with lower levels of impulsiveness. As regards the effect on the serotonergic system activity, the most important role is ascribed to TPH2, MAOA, 5HTR2A and SLC6A4 genes. Genetic analyses confirm the hypothesis that low serotonin activity may lead to increased levels of impulsiveness.
Conclusions. The level of impulsivity is a result of specific interactions between genetic and environmental factors.