Impaired control over drinking predicts changes in alcohol-related consequences over and above alcohol use and facets of impulsivity.

The Theory of Planned Behavior (Ajzen, 1991) states that behavioral intention is the strongest determinant of human behavior. Impaired control (IC; Heather et al., 1993) reflects an intentional failure to consume less alcohol. Cross-sectional studies suggest that IC may mediate relations between impulsivity facets and drinking outcomes but there is only one prospective study examining ICS-Failed-Control (Leeman et al., 2009) and it did not account for effects of impulsivity-facets. Our study sought to address this gap in the literature by examining ICS-Failed-Control as a mediator of relations between impulsivity facets and alcohol-related consequences. We fit a three-wave cross-lagged panel model in a sample of 448 young adults (21-23) from an alcohol challenge study with longitudinal follow-ups (6 and 12 months). Participants completed the UPPS-P, TLFB Interview, the ICS-Failed-Control scale and the YAACQ. Although IC did not mediate effects of impulsivity on alcohol consequences, IC significantly predicted changes in alcohol-related problems at the12-month follow-up, accounting for effects of UPPS-P constructs as well as alcohol use. Lack of premeditation predicted change in alcohol use from baseline to 6-month follow-up and alcohol use (at 6-months) mediated the effect of premeditation (at baseline) on alcohol consequences (at 12-months). Our findings suggest that ICS-Failed-Control is not a mediator of the effects of impulsivity but is a unique predictor of consequences. Future studies should assess UPPS-P constructs earlier in adolescence to identify potential prospective links between UPPS-P constructs and IC.