Long-term test-retest reliability of delayed reward discounting in adolescents.

Delay discounting (DD), a decline in subjective value of a reward with increasing temporal delay in receipt of that reward, is an established behavioral indicator of impulsivity. Preference for smaller-immediate over larger-delayed rewards has been implicated in the basic neurobehavioral mechanisms of risk for addictive disorders and related externalizing psychopathology. Establishing long-term stability of DD in adolescence is a necessary step towards its validation as an intermediate phenotype, or marker of risk, in neurobiological and genetic studies. Previous studies have demonstrated moderate to high test-retest reliability of DD, however, these studies utilized adult samples and examined relatively short retest intervals. Due to continuing development of brain and behavior, stability of temporal discounting behavior in adolescence may differ from that in adulthood. Here, two cohorts of adolescents aged 16 (n=126) and 18 (n=111) were administered a computerized test of DD and re-tested two years later. DD rate showed a modest but significant decrease with age, suggesting a reduction in overall impulsivity from middle to late adolescence. Significant test-retest correlations were observed in both cohorts (.67 and .76, respectively, p<.001) indicating longitudinal stability of individual differences in decision-making behavior during middle and late adolescence. This article is part of a Special Issue entitled: insert SI title.