COMT allele (Met(158)) modulates facial emotion recognition in bipolar disorder I mood episodes and in healthy controls

Abstract

Background: One of the many cognitive deficits reported in Bipolar Disorder (BD) patients is facial emotion recognition (FER), which has recently been associated with dopaminergic catabolism. Catechol-O-methyltransferase (COMT) is one of the main enzymes involved in the metabolic degradation of dopamine (DA) in the prefrontal cortex (PFC). The COMT gene polymorphism rs4680 (Val 158 Met) Met allele is associated with decreased activity of this enzyme in healthy controls. The objective of this study was to evaluate the influence of Val158 Met on FER during manic and depressive episodes in BDI patients and in healthy controls. Materials & Methods: 64 BD type I patients (39 in manic and 25 in depressive episodes) and 75 healthy controls were genotyped for COMT rs4680 and assessed for FER using the Ekman 60 Faces (EK60) and Emotion Hexagon (Hx) tests. Results: Bipolar manic patients carrying the Met allele recognized fewer surprised faces, while depressed patients with the Met allele recognized fewer angry and happy faces. Healthy homozygous subjects with the COMT Met allele had higher FER scores on the Hx total score, as well as on disgust and angry faces than other genotypes. Conclusion: This is the first study suggesting that COMT rs4680 modulates FER differently during BD episodes and in healthy controls. This provides evidence that PFC DA is part of the neurobiological mechanisms of social cognition. DA receptor stimulation alterations during BD mood episodes might explain the contrasting results found in BD compared to controls. Further studies on other COMT polymorphisms that include euthymic BD patients are warranted.