Vieillissement non pathologique des fonctions exécutives : influence du polymorphisme nucléotidique Val108/158Met du gène COMT

Introduction. According to the Dual-State Theory of prefrontal cortex dopamine, Val/Val polymorphism of the COMT gene would favor better flexibility abilities, whereas Met/Met carriers would favor better stability abilities. These genotypic effects should be magnified in older people, as a decrease in cognitive resources increases the influence of individual genetic differences on cognitive performance. Therefore, the aim of the study is to investigate the influence of the COMT Val108/158Met nucleotide polymorphism on executive functions in normal aging. Method. We assessed the executive processes of inhibition, shifting, and updating thanks to many different tasks in groups of young (n = 55) and aged participants (n = 45) carrying one of the three polymorphisms of the COMT gene (Val/Val, Val/Met, Met/Met). T-tests between our two groups (Young versus Aged) but also a 6 (Group: Young-Met/Met, Young-Val/Met, Young-Val/Val, Old-Met/Met, Old-Val/Met, and Old-Val/Val) X 3 (Executive functioning: Inhibition, Shifting, and Updating) repeated measure ANOVA with Executive functioning as within-subject factor (p < .05) were carried out. Results. Young and old participants significantly differed on the three executive functions. The comparison of genotypic groups showed no significant differences in young or older participants respectively. Interestingly, the Old-Val/Val group showed a lower performance than the young one on inhibition tasks. Discussion. As expected, we found an age effect on all the executive functions. The significant difference between the Young-Val/Val and the Old-Val/Val groups on inhibition suggests an age-related decrease in abilities requiring a stability component in individuals possessing a less favoring genotype for this component