Associação de polimorfismos do sistema dopaminérgico com a Tarefa de memória de trabalho visuoespacial e comportamento cortical

Abstract

The neurotransmitter dopamine plays an important role in the executive modulation of cognitive tasks, as well as in working memory tasks. Although the dopaminergic system is hereditary, still isn’t well known about the genetic basis of visuospatial working memory capacity related to it. In view of this, studies which associate genetic loci and phenotypes with this cognitive capacity are essential for a better understanding of the process. Therefore, the objective of this study was to associate the genetic polymorphisms DRD2/ANKK1-TAQ1A, SLC6A3 3'-UTR VNTR, SLC6A3 intron 8 VNTR and COMT Val158Met to performance in the visuospatial working memory task and the neurophysiological activity of the frontal cortex. A total of 149 healthy, right-handed male volunteers with a mean age of 22.77 ± 2.97 years, aged between 18 and 32 years, were selected. Concomitantly to the performance of the task of visuospatial working memory, the neurophysiological variable of the frontal cortex was analyzed by means of the absolute power of the alpha and theta band. The highest genotype frequencies for each polymorphism were: 47% A2/A2 for DRD2/ANKK1-TaqIA; 54.20% 10R/10R for SLC6A3 3'-UTR VNTR; 54.41% 6R/6R for the SLC6A3 intron 8 VNTR; and 44.3% A/G for the COMT Val158Met. All polymorphisms are in Hardy-Weinberg equilibrium (p> 0.05). Analyses of the two-way mixed factor ANOVA showed no statistically significant difference between polymorphism clusters and the error in detecting the target during the MT task (p> 0.05). However, binary logistic regression based on the frequency groupings of the VNTR intron 8 polymorphism in association with the spatial variables indicated a statistically significant association for the X axis (horizontal plane) in the working memory task (p = 0.0001). Neurophysiological analyzes through the three-way mixed factorial ANOVA showed that different genotypic groups for the polymorphisms studied showed variations in the absolute power of the alpha and theta band in different cortical regions (p≤0.05). In the face of these analyzes, it is evident that the cognitive capacity, under a given visuospatial work memory task, may be related to the genetics of the individual.