Striatal bases of temporal discounting in early adolescents.

Steeper rates of temporal discounting-the degree to which smaller-sooner (SS) rewards are preferred over larger-later (LL) ones-have been associated with impulsive and ill-advised behaviors in adolescence. Yet, the underlying neural systems remain poorly understood. Here we used a well-established temporal discounting paradigm and functional MRI (fMRI) to examine engagement of the striatum-including the caudate, putamen, and ventral striatum (VS)-in early adolescence (13-15 years; N = 27). Analyses provided evidence of enhanced activity in the caudate and VS during impulsive choice. Exploratory analyses revealed that trait impulsivity was associated with heightened putamen activity during impulsive choices. A more nuanced pattern was evident in the cortex, with the dorsolateral prefrontal cortex mirroring the putamen and posterior parietal cortex showing the reverse association. Taken together, these observations provide an important first glimpse at the distributed neural systems underlying economic choice and trait-like individual differences in impulsivity in the early years of adolescence, setting the stage for prospective-longitudinal and intervention research.

Trait impulsivity during early adolescence predicts steepness of alcohol use escalation across adolescence.

BACKGROUND AND AIMS: Alcohol use during adolescence is a significant public health concern with serious implications. Both early initiation and rate of escalation of alcohol use during adolescence forecast long-term alcohol-related difficulties and alcohol use disorders (AUDs), underscoring the need to understand psychological factors that contribute to these risk behaviors. One factor that contributes to alcohol use during adolescence is trait impulsivity. The purpose of the present prospective study was to examine associations between trait impulsivity and changes in alcohol use from early adolescence through late adolescence. METHODS: Two hundred forty-six participants (45% female; M age = 13.06; 52.5% Caucasian ethnicity) were drawn from a larger study. Levels of impulsivity and alcohol use were measured at every assessment using self-report questionnaires. Data were analyzed using a latent growth modeling approach (LGM) and fit was examined across four indices. RESULTS: Consistent with previous studies, our findings indicate that trait impulsivity decreased and alcohol use increased during adolescence, and initial levels of impulsivity were associated with concurrent levels of alcohol use. Further, level of trait impulsivity during early adolescence predicted the rate of escalation of alcohol use during adolescence. CONCLUSIONS: In the present research, trait impulsivity assessed during early adolescence predicted the steepness of alcohol use escalation during adolescence, a variable with significant prognostic value for long-term AUDs and behavioral problems. This research underscores the importance of understanding trait impulsivity during early adolescence, and suggests that early trait impulsivity may have predictive value with respect to later alcohol abuse and behavioral problems.