COMT Val158Met polymorphism, verbalizing of emotion and activation of affective brain systems

Genetic variation in the catechol-O-methyltransferase (COMT) Val158Met polymorphism has been shown to influence performance on cognitive and emotional tasks. Specifically, it has been suggested that the Met allele might be less advantageous than the Val allele with respect to emotional processing. This study addresses the question whether the presence of the Met allele is directly related to both lower emotional verbalizing proficiency and differences in brain activation during emotional processing. Specifically, we investigated whether COMT genotype would be associated with differences in activation in cortical midline structures during valence evaluation of words. Forty participants ranging from low to high on the verbalizing subscale of the Bermond-Vorst Alexithymia Questionnaire (BVAQ) were genotyped for the COMT Val158Met polymorphism. During fMRI, they evaluated the valence of emotional words. Met homozygotes reported more difficulties in verbalizing their feelings. In addition, the Met allele was associated with attenuated brain activation in posterior cingulate gyrus and precuneus during valence evaluation. We conclude that the Met allele modulates neural activation in regions associated with emotional awareness. Our findings may contribute to understanding the neural correlates of susceptibility for affective disorders.