Association between the Catechol-O-Methyltransferase (COMT) Val158Met Polymorphism and Alexithymia in Patients with Obsessive-Compulsive Disorder

PURPOSE Alexithymia, defined as a deficit in the ability to recognize and describe one's own feelings, may be related to the development and maintenance of obsessive-compulsive symptoms. The aim of this study was to evaluate the association between the catechol-O-methyltransferase (COMT) Val¹⁵⁸Met polymorphism and alexithymia in patients with obsessive-compulsive disorder (OCD). MATERIALS AND METHODS We recruited 244 patients with OCD (169 males, 75 females). Alexithymia was assessed using the 20-item Toronto Alexithymia Scale (TAS-20), and genotyping of the COMT Val¹⁵⁸Met polymorphism was evaluated. RESULTS Patients with the COMT Val/Val genotype had significantly higher total and "difficulty identifying feelings" (DIF) subdimension scores than those with the Val/Met or Met/Met genotypes. Patients with the COMT Val/Val genotype had significantly higher "difficulty describing feelings" (DDF) subdimension scores than those with the COMT Val/Met genotype. However, there were no differences in the scores for the "externally oriented thinking" (EOT) subdimension among the three genotypes. CONCLUSION These results indicate that the high-activity Val allele of the COMT Val¹⁵⁸Met polymorphism is associated with increased alexithymic traits in patients with OCD. The present finding suggests that alexithymia is an endophenotype of OCD that is mediated by the COMT Val¹⁵⁸Met polymorphism.