Factors that increase risk for alcohol-induced blackouts in high-intensity drinking young adults.

Background: Alcohol-induced blackouts are prospectively associated with negative drinking outcomes. While typically requiring heavy drinking, blackouts are not reported on all heavy drinking events or by all individuals who drink heavily. This study extends previous research by identifying the young adults most likely to experience blackouts assessed prospectively. Hypotheses focused on previously supported (female sex, White race, younger age, family history of alcohol problems, lower subjective response to alcohol, and higher tolerance) and novel predictors (possible traumatic brain injury; TBI) of alcohol-induced blackouts.

Methods: Young adults (n = 203, 57% female, M_age = 22.07) recruited for high-intensity drinking (8/10+ drinks/occasion for females/males) completed a baseline survey and a 28-day ecological momentary assessment protocol. Hierarchical linear modeling was used to test between-person predictors of fragmentary (temporary) or en bloc (permanent) blackout likelihood during the 28 days, and moderators of the effect of day-level estimated blood alcohol concentration (eBAC) on blackout likelihood.

Results: Controlling for event-level and average eBAC, both types of blackouts were more likely among those with higher subjective response to alcohol. Fragmentary blackouts were more likely among younger participants and those with possible prior TBI. Day-level eBAC was more strongly associated with both types of blackouts among non-Hispanic White participants and those with lower mean eBACs. Day-level eBAC was most strongly associated with fragmentary blackouts among those with a first-order family history of alcohol problems.

Conclusions: Younger age and greater sensitivity to alcohol may confer risk for blackouts above and beyond intoxication levels. Future work is needed to understand mechanisms that explain why these factors confer risk for blackouts.