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Alcoholic Blackouts Related To Genetic Factors, Not Amounts Consumed

Posted in Alcohol Abuse

Two new studies of alcoholic brown-outs and black-outs found that they occur because of individual or even genetic causes, and that people who have them are more likely to be injured as a result of drinking.

It was commonly known that drinking alcohol causes memory deficits in some individuals. These deficits can be minor difficulties in remembering the events that occurred during a time of drinking, which are called "alcoholic brown-outs," or they can be so severe that the person has no recollection whatsoever of the time in question, which is an "alcoholic blackout." The new research indicates that the amount of memory impairment does not always depend upon the amounts of alcohol the person drank.

The first study involved 24 college students who were all heavy drinkers, although only some had histories of alcoholic blackouts. Dr. Reagan Wetherill of the University of Pennsylvania hooked up all 24 participants to brain scanning equipment, and then gave them memory tests when they were sober, and then again after they had been drinking.

The brain scans of the participants looked very much alike while they were sober, but very different after they had a few drinks. The ones prone to blackouts had less activity in parts of their brains responsible for creating memories from experiences and regions involved with attention and cognitive functioning.

"It could be that their brains are just wired differently. Or it could be underlying things going on, like differences in dopamine levels," Dr. Wetherill said. "Some people are made differently and are able to handle things such as alcohol and others just aren’t. …The fragmentary blackout is basically partial memory loss after a drinking episode. You can remember bits and pieces of things, once you are given clues. You are conscious and participating in these complex behaviors, but the brain isn’t necessarily online, taking in the information and remembering what’s going on."

"Our findings highlight the fact that alcohol impairs brain functioning and some people may be more vulnerable to alcohol’s effects than others," she said. "Just because your friend may be able to drink a certain number of drinks and appear to be functioning fine, it does not mean that you or everyone else can."

This study appears in the journal Alcoholism: Experimental and Clinical Research.

The second study followed 986 college students, all heavy drinkers, from the University of Michigan and four other schools. The men averaged 82 drinks a month, and the women, 59. The ones who experienced alcoholic black-outs were more likely to land up in medical emergency rooms during the one-year period under study. Typical injuries were cuts, broken bones and head injuries, costing their universities over $500,000.

Marlon Mundt, a lead author of the study, said that identifying students who have blackouts could be a way of finding those most at risk for injuries. He said that black-outs were not related to the amounts of alcohol consumed, and that people exposed to alcohol in the womb were more likely to have them as well as those with certain genetic factors.

This study appears in the journal Health Affairs.