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This study, from a well-respected group of investigators, received a lot of publicity when it appeared in the Journal of the American Medical Association in March 2003. The investigators, who are involved in a large study of almost 6,000 adults over age 65, focused on 373 men and women who developed dementia, comparing them with 373 persons who did not develop dementia.

Less than one alcoholic drink a week reduced Alzheimer Disease risk by 40 percent. One drink a week or up to one drink a day reduced risk further (by 57 percent). One to two drinks a day provided less protection (35 percent reduction), and more than two drinks a day produced no protection. With dementia due to reduced blood supply to the brain, a drink a week to up to one drink a day reduced risk by 40 percent, but one to two alcoholic drinks a day was less effective, reducing risk by only 20 percent.

The authors concluded “our results are consistent with the hypothesis that light to moderate drinking has a protective effect on long-term cognitive function”.

Commentary: There are several reasons for being very cautious in interpreting this study.

First, most other studies do not find that alcohol is protective, and one of the two studies said by the authors to be supportive showed the major beneficial effect was for those drinking one to three drinks a day; that is not impressive support of this study which found most protection with a lesser usage.

Second, the finding of a significant benefit in reducing risk of Alzheimer’s from less than one alcoholic drink a week makes absolutely no sense.

Third, one to two drinks a day, not an excessive amount, was found to be of much less benefit than one drink a week up to one drink a day. That, too, is hard to explain. It would be anticipated that one to two drinks a day, a moderate alcohol intake, would provide greater benefit, not less.

It is reasonably clear that a drink or two a day is good for the heart. It is not clear that moderate drinking is good for the mind or that it will reduce the risk of dementia or Alzheimer’s; indeed, the evidence is not at all persuasive.

McKanal, K.J., et al. Prospective study of alcohol consumption and risk of dementia in older adults. Journal of the American Medical Association. Vol 289 (March 19) Pgs 1405-1413. 2003.

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