How Blackouts Affect the Brain

Blackouts, defined as periods of time which cannot be recalled, are associated with alcoholism and acute alcohol intoxication. Blackouts occur not only in alcoholics but in social drinkers as well, and physical dependence on alcohol is not a prerequisite for experiencing a blackout. Inexperienced drinkers often drink large amounts of alcohol quickly and as a result experience blackouts. Persons experiencing a blackout often engage in destructive or dangerous behavior of which they later have no recollection. Women are at higher risk than men of experiencing a blackout due to the different ways in which men and women metabolize alcohol.

Prevalence of Blackouts among Social Drinkers

Dr. Aaron M. White, assistant research professor in the Department of Psychiatry of Duke University, has done clinical research into the effects of alcohol on the brain as well as conducting surveys on the experiences of social drinkers. The results of a survey of 772 college students conducted by Dr. White and his colleagues suggest that blackouts are more common among social drinkers than was previously surmised. The survey produced the following results:

  • 51% of the students reported having experienced a blackout at some point in their lives
  • 40% reported having experienced a blackout in the past year
  • 9.4% of those who reported drinking in the two weeks prior to the survey reported having experienced a blackout during that time

Effects of Alcohol on Memory Transfer

Dr. White uses an easy to understand analogy to summarize the effects of alcohol on the brain: “If recreational drugs were tools, alcohol would be a sledgehammer.” According to Dr. White and many researchers and experts on the effects of alcohol, alcohol negatively affects virtually every process and function of the brain including memory. Any amount of alcohol impairs brain function, but impairment increases with increased doses of alcohol. However it is not only the amount of alcohol consumed but also the rapidity with which it is consumed that increases its effects. Consuming alcohol rapidly, especially on an empty stomach, greatly increases its effects. A blackout can occur with a surprisingly small quantity of alcohol, if it is consumed quickly enough. Binge drinking, defined as consuming four or more drinks in two hours for women and five or more drinks in two hours for men, can easily lead to a blackout.

Although alcohol impairs memory in various ways, blackouts occur when alcohol disrupts the transfer of memories from short-term memory to long-term storage. In Dr. White’s clinical studies test subjects who were intoxicated were able to remember information given to them for short periods of time but were consistently unable to recall that same information after the intoxication had worn off. Studies conducted by other researchers over the years (Goodwin et al [1969, 1970], Ryback [1970], Parker et al [1976], Lister et al [1991], Acheson et al [1998]) have reached similar conclusions.

Questions about Blackouts or Alcohol’s Effects on Memory?

If you have any questions about the ways that alcohol affects brain function and memory, are worried about the effects of binge drinking on a loved one or are concerned about the role alcohol plays in your life, call us. Our helpline is toll free, and we are available 24 hours a day.