Research findings on the role of the dopaminergic and noradrenergic system, crucially driven by COMT activity, in mediating emotional processing is also not unequivocal: reports of increased norepinephrine availability to reverse the negative bias in information processing characterizing mood and anxiety disorders and to reduce amygdala response to fearful faces [95], [96] support the present finding of the more active COMT val allele – conferring decreased norepinephrine availability – to increase the defensive startle reaction to aversive emotional stimuli. This evidence concerns the gene COMT and anxiety disorder.