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Chronic Drinking May Damage Brain, Memory

Posted on: Tuesday, 24 October 2006, 18:00 CDT

By CHRISTINE DELL'AMORE

Chronic, heavy drinking may damage the part of the brain related to learning and short-term memory, researchers have found.

In a recent study, alcoholic men had lower hippocampus volumes than men without a drinking history. A lower volume could mean a loss of tissue in that part of the brain.

Although previous studies have shown a similar effect, this study was better controlled ... making the findings more believable, study author Dr. Gary Wand, a professor of medicine at Johns Hopkins University School of Medicine, said in a statement.

The study, led by Dr. Thomas Beresford of the University of Colorado Health Sciences Center, will be published in the November issue of Alcoholism: Clinical & Experimental Research.

Beresford and colleagues analyzed magnetic resonance imaging scans of eight adult male veterans who were also alcoholics, as well as eight veteran non-alcoholics. The researchers applied stringent criteria to their selection: The veterans had to be regular, chronic heavy drinkers -- at least five drinks a day at least three days a week -- recent heavy drinkers and alcohol-dependent.

The non-alcoholics were similar to the alcoholics by age and ethnicity, and were also selected for their low incidence of alcohol intake.

Likewise, the researchers were careful to exclude people with certain psychiatric illnesses, such as post-traumatic stress disorder, which some scientists believe may make the hippocampus smaller.

The hippocampus, responsible for the formation of new memory, is divided into two structures -- the right and the left, which are located in the right and left temporal lobes of the brain.

The researchers discovered total hippocampus volume, as well as the left hippocampus volume, shrank in the alcoholic men. The right hippocampus lost volume, but not as much as the left.

Previous research has shown alcohol impairs the ability to form new memory. For example, a person who can't remember his behavior after a night of drinking has experienced blocked hippocampus function.

It's unknown whether long-term drinking creates permanent damage, or kills hippocampus cells. Chronic alcoholics who are otherwise intelligent often have terrible memories, which begs the question: if alcohol affects the hippocampus, does chronic drinking damage the hippocampus? said Scott Swartzwelder, a professor of psychiatry at Duke University Medical Center.

Animal research has established a strong link between chronic alcohol intake and damage to the hippocampus, but observational studies in humans have remained inconclusive.

Many scientists cite poorly designed studies that have not excluded subjects with histories of other brain disorders as a possible reason.

Other conditions, such as chronic stress and Alzheimer's disease, are also associated with injury to the hippocampus.

Beresford's more exclusive study concluded that chronic, heavy drinking exerts a unique and selectively injurious effect on the hippocampus.

However, the study was observational, and it's still unclear whether heavy, long-term alcohol consumption really hurts the hippocampus.

There were also several limitations to the research. For one, the study sample size was small, and it did not include women.

Likewise, the study subjects were observed at one point of time: middle-age. It's unknown whether people with smaller hippocampi simply drink more, possibly due to a genetic proclivity.

Studying the men at various points in their lifetime would provide a better picture of what happens to the brain. For instance, animal research has shown the brain is most sensitive to alcohol during adolescence, and so chronic exposure during youth may cause more damage to the hippocampus, said Swartzwelder.

Overall, the study adds evidence to the hypothesis of long-term damage, he said.

One of the nicest things about it is that it fleshes out a long-standing chunk of animal research and extends it to humans, he said.

Beresford and colleagues plan to continue studying the veterans, focusing on whether the hippocampus can heal itself after alcohol damage, and if so, what scientists can do to accelerate the healing process.

Source: United Press International

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