Today DAPA launched a new poster campaign on campus about blackouts. Blackouts refer to a form of alcohol-induced memory loss, resulting in failure to form long-term memory during the duration of blackout. There are two main types of blackout: fragmentary and en bloc.
En bloc blackouts are what most people think of when they hear that someone has “blacked out.” It is when an entire chunk, or block, of memory is missing. Generally there is a definite point of onset for the en bloc blackout, but it is difficult to tell when the blackout ends because most people fall asleep while still blacked out. A person’s first new memory after an en bloc blackout is thus usually that of waking up, oftentimes disoriented and without memory of how he or she got there.
Fragmentary blackouts, sometimes called “brownouts,” involve partial blocking of memory formation while intoxicated. It is as if there are small pieces missing from the overall picture. People are oftentimes unaware that they are even missing pieces from the intoxication period until they are reminded. Sometimes being reminded helps trigger partial recall of the forgotten memories. Fragmentary blackouts seem to be the more common form of blackout.
What causes blackouts?
Blackouts are primarily due to suppression of neural activity in the hippocampus, a region of the brain involved in transferring events from short-term memory to long-term memory. Thus, intoxicated people during a blackout can oftentimes recall things from short-term memory (they can recall something they were just told), but do not retain the information long-term.
A key contributing factor to blackouts seems to be the rate of B.A.C. (Blood Alcohol Content) rising. In a study, it was observed that participants who experienced slow rising B.A.C. did not black out despite becoming heavily intoxicated by the end. Therefore blackouts might not just depend on final B.A.C. level (how much you drink), but rate of B.A.C. rising (how fast you drink).
How serious is blacking out?
Experiencing blackouts is one of the strongest predictors of someone developing long-term problems with alcohol. Also there is evidence suggesting that once a person alters his/she brain chemistry by blacking out, he/she might become more prone to blackouts in the future, even at lower blood alcohol levels.
Did you know?
Women are more prone to blackouts (both en bloc and fragmentary) than men, even when consuming comparable doses of alcohol.
Mixing alcohol with certain drugs significantly increases the risk of blacking out, especially if the other drugs have memory suppressive functions of their own. For example, using marijuana or benzodiazepene sedatives (“benzos” like Valium and Rohypnol) with alcohol greatly increases risk of blackout.
Information gathered from:
Aaron White. 2004. What Happened? Alcohol, Memory Blackouts, and the Brain. National Institute on Alcohol Abuse and Alcoholism. http://pubs.niaaa.nih.gov/publications/arh27-2/186-196.htm
Ryan Travia, Director, Office of Alcohol & Other Drugs Services
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