Blackout (alcohol-related Amnesia) - Causes

Causes

Blackouts are commonly associated with the consumption of large amounts of alcohol; however, surveys of drinkers experiencing blackouts have indicated that they are not directly related to the amount of alcohol consumed. Respondents reported they frequently recalled having "drank as much or more without memory loss," compared to instances of blacking out. Subsequent research has indicated that blackouts are most likely caused by a rapid increase in a person's blood-alcohol concentration. One study, in particular, resulted in subjects being stratified easily into two groups, those who consumed alcohol very quickly, and blacked out, and those who did not black out by drinking alcohol slowly, despite being extremely intoxicated by the end of the study.

In another study hospital file data showed of 67 participants 39 had reported a blackout. The presence or absence of blackouts was cross-tabulated against various measures of alcohol problem severity. The presence of blackouts was associated to some degree with some indications of severity such as withdrawal and loss of control, but not with duration of problem drinking, physical complications or abnormal liver function.

The presence of blackouts was related to some measures of severity of the problem – withdrawal symptoms and loss of control. The hypotheses that blackouts either reflect a general vulnerability to the cerebral consequences of alcohol abuse or are associated with other forms of more enduring cognitive impairment did not receive any support. In another study which looked at subjective responses to alcohol as a prime for 21st birthday alcohol consumption subjective responses to the initial drink were viewed as a prime for more alcohol consumption during 21st birthday celebrations. Current findings show that subjective responses to alcohol have direct effects on both the final BAC achieved and on the experiences of blackouts and hangover that are not explained by level of intoxication. Where a variety of social factors, such as peer pressure and 21st birthday traditions such as 21 shots may influence the amount of alcohol people consumer, their subjective experiences with alcohol have clear influences on both consumption and the physiological consequences of drinking. These physiological responses to alcohol may have a biological vulnerability that extends beyond the dose-dependent effects of alcohol

Self reports from another study showed that 63% of patients in the study gulped their drinks rather than sipped. Five patients recollected vomiting during the drinking episode while 32 drank on an empty stomach and 41 drank more than originally planned. During the drinking episode 31% subjects described blackouts, 20% described grayouts, and 49% reported no amnesic episode.

Childhood sexual abuse in college women moderated the relationship between dissociation levels and problematic drinking distinct from frequency of blackout experiences. Though research to date had yet to examine this specific relationship in college women, results are consistent with previous clinical reports that dissociative symptoms are most likely to occur in trauma survivors engaging in added risk factors such as substance use. Particularly concerning, college women are more vulnerable to alcohol-related sexual assault as alcohol consumption increases and in the case of women with CSA, problematic drinking heightens the risk of revictimization.