Healthy adolescents differ from adults in cognitive abilities associated with the prefrontal cortical region

Abstract

Adolescence marks the beginning of rapid biological changes in brain structure and connectivity, however, these developmental changes do not happen simultaneously. The neurons of the prefrontal region of the brain seem to develop slowly, as they undergo a delicate process of synaptic pruning and myelinization of axons. Findings regarding the prolonged development of this region are in line with growing evidence from literature and “everyday” experience which suggests that adolescents are more prone to risk-taking, faulty decision making, and cognitive biases. Due to the incomplete process of myelination in the immature frontal lobes, the efficiency of information processing might be limited in adolescents compared to adults, which could lead to evident differences in cognitive abilities associated with this region i.e. planning, executive functions, and inference abilities. The purpose of this study was to determine whether adolescents’ performance in tasks employing these cognitive abilities differs from that of adult subjects. Reasoning and inference abilities were assessed via Wason Selection Test (WST). Executive functions including inhibitory control and attention shifting performance were estimated through reaction time on Stroop Color-Word Test and Trail-Making-Test respectively. The possibility of predicting the performance in the reasoning task based on the achievement in the tests of executive functions was explored as well. The sample consisted of 20 adult subjects and 20 healthy adolescents (gender ratio balanced). Logical reasoning ability was assessed through Significant differences were found between the groups in both WST achievement and executive functions tests’ performance, the latter not being a significant predictor of successfulness in the reasoning task. These results suggest that although the assessed executive functions are not an underlying process of logical reasoning, both are significantly impaired in adolescents compared to adult subjects. The implications of these findings for education programs and initiatives aimed at lowering risk-taking tendencies in adolescents are discussed.