- Alcohol blackouts, 'en bloc' or fragmentary, are a common consequence of heavy drinking.
- Research shows that people who experience fragmentary blackouts (FBs) are more likely to misremember drinking experiences after alcohol is consumed.
- These same individuals report strong positive expectations about future alcohol consumption.
- Researchers believe that some memory-impaired drinkers 'fill in the gaps' with information that conforms to an existing belief system, which may in turn lead to heavier drinking.
Although alcohol-induced amnesiac episodes, commonly known as "blackouts," are not currently used to diagnose alcoholism, they are generally regarded as a warning sign of problem drinking. In fact, blackouts may contribute to problem drinking. A study in the April issue of Alcoholism: Clinical & Experimental Research has found that heavy drinkers who experience fragmentary blackouts (FBs) are more likely to misremember drinking experiences while simultaneously reporting strong positive expectations about future alcohol consumption.
"There are two types of blackouts," said Kim Fromme, associate professor of psychology at The University of Texas at Austin and corresponding author for the study. "'En bloc' blackouts involve complete memory loss for all events occurring within a particular time interval during intoxication. 'Fragmentary blackouts' (FBs) also involve the failure to recall aspects of drinking events; however, these may reflect just portions, or fragments, of experience for which memory is impaired. Another key distinction between the two types of blackouts is that people can use cues or reminders to help access and recall the content of an FB, whereas the content of an en bloc blackout can never be recovered, regardless of the presence of cues or reminders."
"Although common among college student drinkers, blackouts represent one marker that may improve our ability to identify those at risk of developing alcohol problems," said William R. Corbin, assistant professor in the department of psychology at Yale University. "Many college students believe that they are at decreased risk when they begin to experience blackouts and eventually 'pass out' rather than vomit after drinking heavily. In fact, they are at higher risk because drinking to the blood alcohol level necessary for a blackout leads to increased tolerance to alcohol's effects. 'Increased tolerance' is among the diagnostic criteria for alcohol dependence. Thus, blackouts should not be ignored as a prognostic sign."
Participants in this study were predominantly college students (n=108; 55 males, 53 females), 21 to 30 years of age, recruited via newspaper ads and flyers. Inclusion criteria included reports of weekly binge drinking (5 or more consecutive drinks for males, 4 or more for females). The final sample was evenly distributed into those who had had FBs in the previous year (FB+) and those who had not (FB-); the sample was further divided into those who consumed three alcoholic beverages for the study (the volume of which was regulated by gender and body weight), and those who consumed three alcohol-tasting placebo beverages. Memory formation was assessed prior and subsequent to beverage consumption. Alcohol expectancies were also assessed.
"In the absence of alcohol, the memory ability of those who report FBs does not appear to be any different from those who do not experience these phenomena," said Fromme. "Yet when they drink alcohol, people who experience FBs show poorer memory performance both during intoxication and after detoxification when compared to those who have not experienced blackouts. Alcohol therefore affects the memory of some individuals differently than others."
"Although it is interesting to know that FB+ participants show greater impairment in recall after alcohol consumption," added Corbin, "the most interesting results of this study involve the relations among FB status, alcohol expectancies, and source recall. The results describe a potential mechanism through which blackouts may confer risk for later alcohol problems. Heavy drinkers, in general, are likely to develop memory structures for alcohol effects that are biased toward positive outcomes. The current study suggests that fragmentary blackouts may facilitate this process. When an individual cannot recall aspects of his or her experience after drinking, he or she is likely to 'fill in the gaps' with information that is consistent with their existing belief system. In other words, if you already believe alcohol has primarily positive effects, and you cannot recall what happened after a drinking episode, you are likely to assume that the outcome was positive. This may further bias the belief system, leading to heavier drinking and more alcohol-related problems."
"Our results clarify how alcohol can adversely affect the memory of some individuals differently than others," said Fromme. "Though the more extreme en bloc blackout has been studied and theorized about for several decades, our study sheds light on how a less extreme and much more common type of memory impairment after drinking may contribute to distorted beliefs about alcohol, and ultimately to future negative drinking consequences."
"The primary implication of the results for college students is that alcohol-related experiences, including blackouts, should be taken seriously," said Corbin. "The findings also highlight the importance of alcohol outcome expectancies. Longitudinal studies have demonstrated that alcohol expectancies are predictive of later drinking behavior and alcohol-related problems. The current study provides one possible mechanism through which positive alcohol expectancies may be maintained and/or strengthened. Given the established relation between alcohol expectancies and negative outcomes, this is an important contribution."
Alcoholism: Clinical & Experimental Research (ACER) is the official journal of the Research Society on Alcoholism and the International Society for Biomedical Research on Alcoholism. The lead author of the ACER paper is Bryan Hartzler, a doctoral candidate in clinical psychology at The University of Texas at Austin (currently completing his pre-doctoral internship in the Seattle division of the VA Puget Sound Healthcare system). The study was funded by the National Institute on Alcohol Abuse and Alcoholism.