Depressive rumination and the C957T polymorphism of the DRD2 gene.

Depressed individuals who ruminate have difficulties learning from punishment and suppressing task-irrelevant information. The C957T polymorphism of the DRD2 gene, which affects functioning of D2 dopamine receptors (DRD2) that are expressed predominantly in the indirect pathway of the basal ganglia, has been found to influence suppression and punishment learning. Given these associations, we examined in the present study whether depressive rumination is related to the C957T polymorphism in 317 clinically depressed individuals and 317 never-depressed control individuals. A 2 × 2 (diagnostic group ×C957T polymorphism) analysis of variance conducted on depressive rumination scores yielded a significant interaction of group and C957T: Individuals with two 957C alleles reported higher levels of depressive rumination than did individuals with one or two 957T alleles if they were depressed, but not if they were healthy. The present findings suggest that the dopaminergic system and DRD2 are related to the frequency of maladaptive rumination in depressed individuals. Thus, DRD2 may be an important target for the pharmacological treatment of depressive rumination.