The harmful effects of alcohol intoxication and alcohol abuse on memory are well known—for example, the college student who can’t remember a conversation she had at a party the night before, or the man who wakes up in a hotel room with no recollection of how he got there.
But what may be less well known are the benefits that moderate amounts of alcohol can have on cognitive function. Growing evidence shows that people who drink moderately are at lower risk for memory loss and dementia.
The Evidence on Alcohol and the Risk of Dementia
Researchers looked at the relationship between alcohol and the risk of dementia in a study published in the Journal of the American Medical Association. When the researchers compared data from 373 people with dementia (age 65 and older) and 373 age-matched controls, they found that people who drank one to six drinks of alcohol per week were 54% less likely to have dementia than people who never drank alcohol. People who drank alcohol less often (less than once a week) or somewhat more often (7 to 13 drinks a week) also appeared to have a reduced risk of dementia, but this may have been a chance finding.
Consuming 14 or more drinks of alcohol a week was linked with an increase in dementia risk, although this finding also may have been the result of chance. (In the study, one drink was 12 oz. of beer, 6 oz. of wine, or a shot of liquor.) These results were similar for both Alzheimer’s disease and vascular dementia, and they are in line with the findings of other recently published, large observational studies.
The investigators also found that the effect of alcohol on dementia risk varied according to whether participants had at least one apolipoprotein E (APOE)-e4 allele, a genetic predisposition toward Alzheimer’s disease. In people who did not have the APOE-e4 allele, high levels of alcohol intake were not associated with an increased risk of dementia, even in those who had 14 or more drinks weekly.
For those with at least one APOE-e4 allele, however, the risk of dementia increased significantly with seven or more drinks a week. However, not all studies have found an association between drinking and this genetic predisposition to Alzheimer’s disease.
Why These Effects of Alcohol?
Research has consistently shown that moderate alcohol intake lowers the risks of coronary heart disease and ischemic stroke in older people. Because factors that are good for the heart are often good for the brain as well, many experts believe that alcohol might help protect the brain in the same ways it helps protect the heart. For example, alcohol inhibits blood clotting and raises blood levels of high density lipoprotein (HDL, or “good”) cholesterol, factors that may limit atherosclerosis and help maintain blood flow to and within the brain.
Further, research in rats has shown that low doses of alcohol can increase the release of the neurotransmitter acetylcholine in the hippocampus, which may improve memory function. On the other hand, high doses of alcohol can inhibit the release of acetylcholine and possibly interfere with memory.
Another contributing factor may be the social experiences of many moderate drinkers. People who drink alcohol moderately also tend to have more social contacts than abstainers or heavy drinkers. This social interaction may lessen depression, anxiety, and stress, and help protect against dementia.
Some studies have shown that wine, in particular, protects against dementia. It is possible that the antioxidant compounds in wine, especially red wine, play some role in this effect. However, many studies, including the recent Journal of the American Medical Association study described above, have found that all types of alcoholic beverages—including beer and liquor—have a protective effect.
The Bottom Line on Alcohol and the Brain
Experts do not recommend that people who don’t drink start drinking alcohol as a way to prevent dementia, but for current drinkers, having a drink or two a day for men or a drink daily for women is likely healthy for both the heart and the brain. However, women should be aware that alcohol may increase the risk of breast cancer. One recent study found that women who consumed two to five alcoholic drinks daily had a 41% higher risk of developing breast cancer than nondrinkers. Women who consumed about one alcoholic drink per day had only a slight increase in risk compared with nondrinkers.
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Posted in Memory on November 26, 2005
Reviewed June 2008
