Effects of Genes on Individual Differences in Executive Function Development in Preschool-Aged Children

Abstract

Few studies have examined how individual differences in genes related to the brain’s dopamine system impact the development of higher-level cognitive skills in children. Past research with adults has identified that variants of the dopamine transporter gene (DAT-1) are associated with poorer inhibitory control development, including higher impulsivity and risk-taking. Similarly, genetic variability related to COMT, an enzyme that degrades dopamine, predicts working memory abilities in adults. This study evaluated whether individual differences in the DAT-1 VNTR polymorphism and COMT Val158Met polymorphism predicted the development of executive functions (higher order cognitive skills, including working memory, inhibitory control, and attention shifting) at age 5. On tasks requiring inhibitory control (balloon analogue risk task, delay discounting), we found a non-significant relationship between children’s performance and DAT-1 VNTR genotypes. On tasks examining working memory (spatial span, memory search), children homozygous for the Met allele of the COMT Val158Met polymorphism performed more poorly than their peers with a Val allele. Parent report of inhibitory control and working memory development was unrelated to children’s genotypes, highlighting that differences by genotype are not within the clinical range of abnormality. Overall, our results suggest that the COMT polymorphism is associated with similar effects on preschooler’s working memory abilities as reported in adult studies. However, neither DAT-1 VNTR polymorphism predicted inhibitory control development at preschool age, suggesting that additional environmental factors may have a stronger impact on inhibitory control during early childhood.