Blackouts: the etiology of alcohol-induced amnestic episodes and their effect on alcohol-related beliefs

Blackouts are widely-noted sequelae of heavy drinking, yet understanding of their characteristics, correlates, and consequences is limited. Two distinguishable blackout types exist: 1) en bloc, or full memory loss for all events that occur during intoxication, and 2) fragmentary, or partial memory loss for intoxicated events that may be later recalled after provision of cues. Descriptive aspects of each were explored via self-reported drinking practices of 108 young adults. Both types were reported at a wide variety of blood alcohol concentrations (BACs) above .06 mg%, yet fragmentary blackouts were reported more frequently than en bloc. Further, fragmentary blackouts covaried less often with polysubstance use and elicited less negative evaluations than did en bloc. A placebo-controlled design addressed the etiology of fragmentary blackouts through assessment of memory formation prior and subsequent to alcohol consumption. Findings suggest fragmentary blackouts result from poor retrieval of previously encoded and stored material, and that individual differences in retrieval emerge after alcohol is consumed. Further, one’s recall for source aspects of material—its time and social context—is an important determinant of recall during intoxication. Also examined were relations among fragmentary blackouts and alcohol expectancies. Those who reported prior fragmentary blackouts endorsed stronger outcome expectancies for a range of alcohol effects, and exhibited greater accessibility for positive alcohol concepts presented after beverages were consumed. Further, source recall contributed significantly to the strength of positive alcohol outcome expectancies. The collective findings expand understanding of this complex yet common neuropsychological consequence of heavy drinking.