Alcohol-induced blackouts : lessons learned from examining three risk factors

Alcohol-induced blackouts, one neurobiological consequence of alcohol use, are periods of amnesia for all or part of a drinking event. Risk factors for blackouts include a family history of problematic alcohol use (FH+), early onset of drinking, and subjective responses to alcohol. The objective of this project was to examine how these factors confer risk for blackouts, as well as to what extent blackouts predict a motivation to decrease drinking. Participants were from a 6-year, longitudinal study of first time college students. Self-reported frequency of blackouts, motivation to change drinking behavior, indices of alcohol consumption, and subjective intoxication (i.e., feeling drunk) were assessed annually during Years 4-6. Age at drinking onset (i.e., age at first drink, first high, and first drunk) was assessed at Year 4. FH+, captured at baseline, was coded if participants self-reported that their mother, father, or any of their four grandparents were a possible or definite problem drinker. Overall, 52% to 69% of participants reported experiencing blackouts during Years 4-6. With respect to FH+, women were more likely to report blackouts than men; however, compared with women with a maternal FH+, men with a maternal FH+ were more than twice as likely to report blackouts. Additionally, after controlling for year specific binge drinking, a growth curve model indicated that early onset drinkers reported more frequent blackouts at Year 4. There were, however, no significant effects of acceleration or deceleration in the frequency of blackouts across the three years. Early onset drinkers continued to experience more frequent blackouts compared with those who initiated alcohol use later, despite decreases in binge drinking over time. Finally, in a cross-lagged model, subjective intoxication (i.e., feeling drunk) prospectively predicted experiencing blackouts. Controlling for both objective (e.g., quantity) and subjective intoxication, blackouts at Year 4 predicted greater motivation to change drinking behavior at Year 5, but this motivation did not predict less quantity of alcohol use by Year 6. Altogether, early onset drinking, maternal FH+, and subjective intoxication are robust predictors of blackouts. The underlying mechanisms behind these markers of risk involve both environmental and genetic factors, which likely operate together.