Another polymorphism that is relevant to resilience (Val158Met) is found in the gene that codes for COMT, an enzyme that degrades dopamine and noradrenaline. Individuals with the low-functioning Met158 allele have higher circulating levels of these neurotransmitters. Possibly as a result, they tend to exhibit higher anxiety levels, increased plasma adrenaline levels in response to stress, lower resilience to negative mood states, and increased limbic reactivity to unpleasant stimuli54. Recent functional MRI (fMRI) studies have extended the link between the COMT Met158 allele and increased limbic reactivity to other emotion-processing and reward tasks, and have shown differential cortico-limbic connectivity in Met158 allele carriers, which is further discussed below55.
