The likelihood of alcoholic blackouts has been linked to the speed and duration of intoxication
American scientists conducted a small study among college students and found that the likelihood of alcoholic blackouts was closely related to the rate of intoxication, the duration of its onset and the peak blood alcohol concentration. A report of the work is published in the journal Alcohol, Clinical and Experimental Research.
Alcohol blackout is a form of amnesia in which a person is conscious and able to communicate while intoxicated, but then loses all memory of what happened (partial loss of such memories is sometimes called alcoholic palimpsest). They are usually associated with the amount of alcohol consumed and the stage of alcohol use disorder.
To better understand the risk factors for this phenomenon, Veronica Richards and her colleagues at the University of Pennsylvania invited 79 second- and third-year college students aged 18 to 22 years (average age 20.1 years; 55.7 percent female) to participate. Selection criteria included habitual consumption of four or more servings of alcohol (the standard American serving is approximately 14 grams of pure alcohol) on Fridays and Saturdays, experience of at least one alcohol blackout during the last semester, willingness to wear a wrist-mounted transdermal alcohol sensor from Thursday evening to Sunday morning for four consecutive weeks, and having an iPhone (needed to record information from the sensor).
In addition to wearing the sensor, participants completed a small questionnaire every Friday, Saturday and Sunday between 10:00 and 18:00. The frequency and severity of alcohol blackouts were assessed using the eight-item ABOM-2 scale, and were summed and reduced to the dichotomy "had a blackout" or "did not have a blackout" during processing. Statistical processing of the data was performed using multilevel logistic models.
A total of 486 days of alcohol use and 147 alcohol blackouts were recorded among all participants (at least one occurred in 70 per cent of participants). It turned out that the likelihood of blackouts increased on days when the rate of intoxication (average rate of concentration rise per hour), the duration of its rise (total number of hours the concentration rose) and the peak alcohol concentration were greater - the odds ratio (OR) was 2.69 (95 per cent confidence interval 1.56-5.90), respectively; 4.16 (95 per cent confidence interval 2.08-10.62) and 2.93 (95 per cent confidence interval 1.64-7.11).
Thus, the three indicators studied were found to be independent predictors of alcohol blackout risk. The findings suggest that how a person drinks alcohol, not just how much, should be taken into account when assessing this risk and taking steps to reduce it, the authors of the paper conclude.
Earlier British researchers have shown that, although alcohol impairs anterograde memory, it can improve retrograde - the participants of the experiment better remembered the learnt, if after that drank alcohol in random quantities.