The Relationship Between Valence, Task Difficulty, and the COMT Val 158 Met Polymorphism in Disengagement Processes

The catechol-O-methyltransferase (COMT) Val(158)Met polymorphism (rs4680) moderates dopamine degradation in the prefrontal cortex. It has been shown that the Met allele is associated with an increased reactivity to negative stimuli. With regard to the tonic-phasic dopamine model it is hypothesized that this increased reactivity to negative stimuli derives from deficient disengagement from negative stimuli. The aim of this study was therefore to investigate whether this increased reactivity is reflected in prolonged disengagement from negative pictures. We used a novel forced spatial disengagement task in combination with eye tracking. This paradigm allows for varying task difficulty. Interestingly, contrary to our hypothesis, we found increased disengagement latencies for negative pictures in homozygous Val allele carriers compared to heterozygous participants. This effect was only seen in task conditions demanding less cognitive resources (prosaccade condition). We suggest that the COMT effect on emotional processing is task-specific and therefore heterosis effects can occur.