The influence of Val158Met COMT on physiological stress responsivity

We tested the extent to which the catechol-O-methyltransferase (COMT) Val158Met polymorphism is associated with stress response and pain in both men and women. The participants were assessed on measures of perceived pain and state/trait anxiety in association with their COMT allele status. We also measured cortisol and salivary alpha-amylase (sAA) levels since previous research suggests an association between the COMT Val159Met polymorphism, cortisol secretion, and sAA activity. We found significant differences between methionine (Met) allele carriers and valine (Val) homozygotes following a stress manipulation in sAA levels. Met allele carriers had a stronger sAA response when compared to Val homozygotes. Furthermore, Val homozygotes showed a positive correlation between their sAA levels and trait anxiety at baseline and 20 min post-stress manipulation but displayed a negative correlation with the change in sAA levels from baseline to 20 min post-stress manipulation. Finally, state/trait anxiety was significantly correlated in Met allele carriers. These findings add support to the COMT warror/worrier model which states under stressful situations, increased dopamine levels in Val (warrior) homozygotes affords an emotional advantage relative to Met (worrier) allele carriers, who show an increased reactivity to aversive stimuli. Summary   These findings offer new support for the warrior/worrier model of COMT genotype (rs4680) on human behavior. Twenty minutes following exposure to a cold stress, Val homozygotes (warrior) showed a lower biochemical stress response (salivary alpha-amylase, sAA) relative to methionine (Met) allele carriers (worrier). We further show that the COMT genotype differentially influences state and trait anxiety measures as they relate to stress responses and to each other.