BACKGROUND: While drinking, one must eventually decide between the immediate rewarding effect of alcohol and the delayed reward of a healthier lifestyle. Individuals differ in their devaluation of a delayed reward based on the time required to receive it, the so called delay discounting. Previous studies showed that adolescents discount steeper than adults and that steeper delay discounting was associated with heavier alcohol use in both groups.

METHODS: In a large-scale longitudinal study, we investigated whether higher rates of delay discounting are a developmental antecedent or a consequence of alcohol use during adolescent development. As part of the IMAGEN project, 2220 adolescents completed the Monetary Choice questionnaire as delay discounting measure and the Alcohol Use Disorders Identification Test as well as the Timeline-Follow-Back interview at the ages 14, 16, 18 and 22. Bivariate latent growth curve models were applied to investigate the relationship between delay discounting and drinking. To further explore the consequences of drinking, we computed the cumulative alcohol consumption to correlate it with the development of discounting. A subsample of 221 participants completed an intertemporal choice task during functional magnetic resonance imaging at ages 14, 16 and 18. Repeated-measures ANOVA was used to differentiate the development of neural processing during intertemporal choices between high-risk and low-risk drinkers.

RESULTS: Overall, high rates of delay discounting at age 14 predicted a stronger increase of drinking over 8 years. In turn, an average, moderate alcohol use did not affect delay discounting from age 14 to 22. Of note, we found indicators for less brain activity in top-down control areas during intertemporal choices in those participants who drank more.

CONCLUSIONS: Concluding, steep delay discounting is a predictor rather than a consequence of alcohol use in low-level drinking adolescents. Consideration is given to sampling strategies and reliability concerns for future longitudinal studies.