Longitudinal associations between binge drinking and changes in behavioral and neural threat reactivity in youth.

Problematic alcohol use frequently emerges during adolescence and young adulthood, yet few objective markers reliably capture risk or track early changes in drinking behavior. Reactivity to uncertain threat (U-threat) has been identified as a potential neurobiological risk factor for alcohol misuse; however, no study has examined within-subjects changes in reactivity to U-threat as a function of drinking frequency. Thus, it remains unclear whether reactivity to U-threat reflects a stable vulnerability marker or a dynamic process that tracks within-person changes in alcohol use. To address this gap, youth ages 16-19 (N = 134) in the early stages of alcohol involvement completed startle and neuroimaging versions of the No-Predictable-Unpredictable (NPU) threat task at baseline and 6-month follow-up. Participants were classified into three groups based on changes in binge drinking frequency (decreased, stable, increased). Repeated-measures ANOVAs examined group × time effects on startle potentiation and activation of the anterior insula (aINS) and dorsal anterior cingulate cortex (dACC) during U-threat. Results revealed a significant group × time interaction for startle: youth who increased binge drinking showed heightened startle reactivity to U-threat over time, whereas those who decreased or maintained drinking showed no change. No significant interactions emerged for aINS or dACC activation. Findings indicate that behavioral reactivity to U-threat is associated with short-term changes in binge drinking, suggesting that startle potentiation may reflect a within-person correlate of risk. These results highlight exaggerated U-threat reactivity as a promising psychophysiological target for early detection and intervention.