Light and moderate drinkers may have clearer heads than nondrinkers, according to two new studies that support the growing body of research showing that alcohol can slow the rate of cognitive decline as people age.
The research, published recently in the medical journals Stroke and Neuroepidemiology, compared the cognitive performance of nondrinkers, light drinkers, moderate drinkers and heavy drinkers, to see if alcohol consumption may be related to brain deterioration.
The Neuroepidemiology study looked at more than 7,000 women between the ages of 65 and 80 to evaluate their brain function, including verbal fluency, attention span, memory and motor speed.
"Our research confirms other studies suggesting that for older women who choose to drink, and are not restricted from drinking for medical reasons, moderate alcohol intake is not harmful for cognition and may provide some mental benefits," said lead author Mark Espeland of the Wake Forest University School of Medicine in North Carolina. The current study is a follow-up to a previous study he authored, and supports its results.
The research team, which included scientists from medical centers in five other states, culled data from two larger studies: the Women's Health Initiative Memory Study, a national assessment of the effects of hormone therapy on dementia and cognitive function, and the Women's Health Initiative Study of Cognitive Aging, which involved annual standardized testing of cognitive performance.
For Espeland's study, the results of each woman's tests were averaged to create one "3MS" score, a standard in the medical field for indicating overall cognitive abilities. The higher the score, the better the brain worked. Moderate drinkers--those who consumed two to three drinks a day--had the highest 3MS score, at an average of 96.99. In contrast, the average score for nondrinkers was 96.47. This difference was considered significant in the study.
Light drinkers also performed better on the tests than nondrinkers, scoring an average of 96.71. Even women who reported consuming four to five drinks a day scored 96.59. However, the heaviest drinkers, at six or more a day, clocked in at 95.94, significantly lower than the nondrinkers. (While not specified in this study, a typical drink is usually around 4 to 5 ounces of wine.)
However, Espeland cautioned, "I think it is premature to think of [drinking alcohol] as a preventive measure, as a clinical trial would be required."
The study published in Stroke looked at a multiethnic population, mainly Hispanic, living in northern Manhattan. Led by Clinton Wright at Columbia University's Division of Stroke and Critical Care, the researchers studied volunteers' carotid arteries, which carry oxygenated blood up through the neck to the brain.
When plaque builds up in the carotid vessels, it acts as a kink in the fuel line, and the lack of oxygen to the brain can lead to a stroke, causing symptoms such as blurred vision and slurred speech. Wright and his team believed that alcohol consumption can lead to improved cognitive performance by helping to keep the carotids clear, as other studies have found that red wine helps keep the arteries around the heart clean.
Instead the study found that "moderate alcohol consumption was independently associated with better cognitive performance in women," when compared with nondrinkers. The women's mental skills did not appear to be related to the condition of their carotid arteries, leading the authors to conclude that "alcohol may impact cognition through a separate pathway."
The researchers examined 2,215 people, who were recruited via random telephone calls, were older than 40 and had never had a stroke. The volunteers were given a barrage of cognitive tests in their native language and underwent a high-resolution ultrasound to measure the amount of plaque in their carotid arteries.
An average of 58 percent of the participants showed some measurable level of carotid plaque. Broken down according to race, 71 percent of whites, 65 percent of blacks and 49 percent of Hispanics had plaque buildup in their carotid arteries.
The volunteers also reported their food intake and alcohol consumption. Moderate consumption was classified, for this study, as anything between one drink a week up to two drinks per day. Light consumption was classified as less than one drink a week, and heavy drinking was considered to be more than two servings a day. (One drink was defined as a 120ml glass of wine, 360 ml of beer, or 45 ml of spirits.)
When the researchers compared the data on carotid blockage to the cognitive test results, they found that lower levels of plaque were not related to better test scores.
However, when Wright and his team looked at the volunteers' alcohol consumption, they found that women who drank moderately performed 26 percent better on the cognitive tests than women who didn't drink. Among women, the light drinkers performed 9 percent better than nondrinkers and heavy drinkers performed 28 percent better, although the study noted that the latter group was too small to effectively measure.
Men did not show the same benefits. Moderate drinkers performed only 8 percent better and light drinkers 1 percent better on the mental tests than nondrinkers, while male heavy drinkers did 6 percent worse. Wright suggested flaws in the study may have led to this result. "There were few men that reported never being drinkers, so we probably just lack statistical power to see the effects in men," he said. "Of course, it is possible that another factor that distinguishes women from men, such as hormone levels, is a mediator."
A Harvard study released last year also found that elderly women can benefit mentally from having up to one drink per day. In addition, other recent research has found that moderate alcohol consumption may reduce the risk of stroke, may not be linked to cognitive decline and may even be related to better cognitive skills.
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