Moderate Drinking May Reduce Cognitive Decline
Problems with memory and brain function, including
Many researchers believe that the cardiovascular benefits associated with moderate drinking may translate into cognitive benefits, since cognitive impairment and cardiovascular disease share many common risk factors. While a number of studies support this notion, some have suggested that moderate drinkers do no better on cognitive tests than nondrinkers.
Until now, most of these studies have been relatively small. But a new study in the January 20, 2005 issue of the New England Journal of Medicine evaluated the association between alcohol intake and cognitive function in over 12,000 older women, and found that drinking up to approximately one drink per day was associated with better cognitive function and less cognitive decline over two years, compared with not drinking at all.
About the Study
This study involved 12,480 women from the Nurses’ Health Study, which includes over 120,000 female registered nurses who were ages 30–55 when the study began in 1976. Every two years, the nurses complete a mailed questionnaire about their lifestyle and health.
For this study, the researchers identified the participants who were 70 years of age and older in 1995. Since antidepressant use is related to both alcohol intake and cognition, women who reported using antidepressants were excluded from this analysis. The women participated in telephone interviews to test their cognitive function, focusing on general cognition and verbal memory, when the study began and an average of two years later.
The researchers used reports of alcohol intake, which were part of the biannual questionnaires, to classify the women as nondrinkers, those who drank 1.0–14.9 grams of alcohol (up to one drink) per day, and those who drank 15.0–30.0 grams of alcohol (1–2 drinks) per day. Women with unstable drinking patterns and those who drank more than 30 grams of alcohol per day were excluded. (Note: a 12-ounce beer, a 4-ounce glass of wine, and 1.5 ounces of liquor contain 13.2, 10.8, and 15.1 grams of alcohol, respectively.)
The researchers adjusted for factors that might influence cognitive function and alcohol intake, including education, cardiovascular risk factors, physical activity, body-mass index, smoking, mental health scores, energy-fatigue scores, social integration, and the use of certain medications and supplements.
Fifty-one percent of the participants were nondrinkers, 44% were moderate drinkers (up to one drink per day), and 5% had higher levels of drinking (1–2 drinks per day).
The researchers found that the moderate drinkers had slightly better cognitive scores than nondrinkers. The scores of women with higher levels of drinking, on the other hand, were not significantly different from those of nondrinkers.
Compared with nondrinkers, the moderate drinkers also had a 20% decreased risk of cognitive impairment, as well as a significantly lower risk of substantial cognitive decline (defined as a change in cognitive function in the worst 10% of the group).
These findings were consistent regardless of the type of beverage consumed (i.e., beer, wine, or liquor). The study was limited, however, because alcohol intake was self-reported, a method which is prone to error and bias. In addition, since the researchers did not look at heavy alcohol intake and only studied the women for a short time (an average of 1.8 years), they could not assess the effects of heavy drinking or moderate drinking over the long-term.
How Does This Affect You?
The results of this study suggest that older women who consume up to one alcoholic drink per day may experience cognitive benefits. These findings support others that suggest moderate drinking reduces both the risk of cognitive impairment and cognitive decline over time.
Researchers don’t yet know exactly how moderate alcohol consumption affects cognition, but a plausible theory has to do with its cardiovascular benefits. Moderate drinking has been associated with elevations in high-density lipoprotein (HDL, or “good”) cholesterol, and improvements in vascular function. Many researchers speculate that moderate drinking may also help preserve vascular function in the brain, which could conceivably prevent small, undetected strokes and improve brain function.
If you are an older woman and already drink moderately, this study suggests that up to one drink per day may protect your brain. However, if you do not drink, this study does not suggest that you start. It is possible that it was not the alcohol that was protective, but some other characteristic of moderate drinkers that the researchers did not anticipate. And it’s important to emphasize that heavy drinking is associated with an increased risk of stroke and heart disease, along with higher rates of depression, certain cancers, liver disease, and motor vehicle accidents.
Harvard School of Public Health
National Institute of Neurological Disorders and Stroke
Mukamal KJ et al. Prospective study of alcohol consumption and risk of dementia in older adults. Journal of the American Medical Association . 2003;289:1405–1413.
Reynolds K, Lewis LB, et al. Alcohol consumption and risk of stroke: a meta-analysis. Journal of the American Medical Association . 2003;289:579–588.
Stampfer MJ, Kang JH, Chen J, Cherry R, Grodstein F. Effects of moderate alcohol consumption on cognitive function in women. New England Journal of Medicine . 2005;352:245–253.
Last reviewed Jan 20, 2005 by
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