No document available.
Abstract :
[en] The COMT val108/158met polymorphism was associated to the dopaminergic modulation in the brain, and therefore stimulated research on its influence for cognitive functioning and particularly working memory. First, a general advantage of carrying the met allele was reported. However, many studies used tasks that did not allow efficiently assessing the contribution of manipulation and maintenance processes in working memory, leading to divergent results, in both young and older populations, resulting in debates about the exact phenotypic effect of the COMT polymorphism. Using fMRI, this study was designed to assess the potential effect of the COMT polymorphism on age-related differences in working memory representations maintenance abilities (Sternberg paradigm). Partial Least Squares method was used to determine the brain-behavior correlations at low, intermediate, and high cognitive demands among young and older groups, homozygous for the val or for the met allele. First, young val/val showed some disadvantages at brain and behavioral level compared to their m/m counterparts. However, in older adults subgroups, the m/m participants tended to show greater age-related difference (when compared to younger adults with similar genotype), suggesting an advantage in carrying the val allele when dopamine signaling is not at optimal efficiency (optimal: young/middle adulthood vs suboptimal: childhood or older ages). These results will be discussed in regard to compensating theories and dopaminergic models accounting for the potential effect of COMT polymorphism on stability/flexibility abilities.
