Neurobehavioral evidence for changes in dopamine system activity during adolescence

Abstract

Human adolescence has been characterized by increases in risk-taking, emotional lability, and deficient patterns of behavioral regulation. These behaviors have often been attributed to changes in brain structure that occur during this developmental period, notably alterations in gray and white matter that impact synaptic architecture in frontal, limbic, and striatal regions. In this review, we provide a rationale for considering that these behaviors may be due to changes in dopamine system activity, particularly overactivity, during adolescence relative to either childhood or adulthood. This rationale relies on animal data due to limitations in assessing neurochemical activity more directly in juveniles. Accordingly, we also present a strategy that incorporates molecular genetic techniques to infer the status of the underlying tone of the dopamine system across developmental groups. Implications for the understanding of adolescent behavioral development are discussed.

Keywords: Adolescence; Brain Development; COMT; Dopamine; Working Memory.

Figure 1

The COMT/Cognition Relationship in 9-17 year-old Healthy Adolescents Adapted from Wahlstrom et al. (2007), this figure illustrates working memory and attentional performance in healthy adolescents as a function of COMT genotype. Working memory and attention were assessed through spatial delayed response, digit span, and spatial span tasks and scored as a standardized composite. The heterozygote Val/Met group performed better than either homozygote group.

Figure 2

Modeling the COMT-Cognition Relationship from Adolescence to Adulthood Changes in the relationship between COMT genotype and cognitive performance as a function of age. In adolescence, Val homozygotes are conferred functional benefits due to developmental increases in dopaminergic availability. Conversely, the performance of Met homozygotes suffers due to excess dopamine (as a result of genotype and age-related increases in dopaminergic availability), which moves them to the right of the inverted U-shaped function.