The flexible mind is associated with the catechol-O-methyltransferase (COMT) Val158Met polymorphism: Evidence for a role of dopamine in the control of task-switching

Genetic variability related to the catechol-O-methyltransferase (COMT) gene (Val(158)Met polymorphism) has received increasing attention as a possible modulator of cognitive control functions. Recent evidence suggests that the Val(158)Met genotype may differentially affect cognitive stability and flexibility, in such a way that Val/Val homozygous individuals (who possess low prefrontal dopamine levels) may show more pronounced cognitive flexibility than Met/-carriers (who possess high prefrontal dopamine levels). To test this, healthy humans (n = 87), genotyped for the Val(158)Met polymorphism at the COMT gene, performed a task-switching paradigm, which provides a relatively diagnostic index of cognitive flexibility. As predicted, Met/-carriers showed larger switching costs (i.e., less cognitive flexibility), F(1,85)=4.28, p<0.05, than Val/Val homozygous individuals. Our findings support the idea that low prefrontal dopamine levels promote cognitive flexibility. (C) 2010 Elsevier Ltd. All rights reserved.