Moderate Wine Drinking Linked to Preserved Cognitive Function
September 14, 2010 — In a Norwegian long-term population-based study, moderate wine drinkers had better cognitive test scores after 7 years' follow-up compared with teetotalers and those who rarely drank alcohol, researchers report in July in Acta Neurologica Scandinavica.
"Our observations support results from other studies which indicate that light-to-moderate wine consumption could protect against cognitive decline and possibly also vascular and Alzheimer's dementia," first author Kjell A. Arntzen, MD, from the departments of Community Medicine and Neurology, University of Tromsø, Norway, and colleagues conclude.
Reached for independent comment on the study, Mary Ganguli, MD, MPH, professor of psychiatry, neurology, and epidemiology at University of Pittsburgh, Pennsylvania, said: "I don't think there is anything dramatically new here, but the study is quite detailed, with a nice big sample, nice long follow-up, [and] breaks down alcohol use into many categories, so it does help build the argument."
Dr. Arntzen and colleagues examined the relationship over 7 years between intake of alcoholic beverages (beer, wine, and spirits) and cognitive function in 5033 stroke-free men and women. The mean age was 58.2 years for the 2806 women in the study and 58.8 years for the 2227 men.
Cognitive function was assessed using 3 standardized tasks: the 12-word memory test, the digit-symbol coding test, and the tapping test. These tasks were chosen, the authors explain, because of their "ability to detect early cognitive decline and their feasibility as screening tests in an epidemiological setting with a large number of participants."
In terms of alcohol consumption, 11.1% of men and 23.1% of women were teetotalers. The majority of subjects reported low alcohol intake (<1 glass/14 days, the reference group); 19.9% of men and 29.9% women drank at this level. The median alcohol intake was 1 drink per 14 days in women and 3 drinks in men. On average, only 1.9% of men and 0.2% of women had more than 2 drinks daily.
According to the investigators, increasing consumption of wine was significantly associated with better cognitive performance at follow-up in both men and women (P for trend ranging from .0003 to .04 in men, and from <.0001 to .002 in women).
In men, moderate beer consumption was also associated with better scores on 2 of the cognitive tests, the authors note, "but the differences in estimates were inconsistent." There was no consistent association between drinking spirits and performance on the cognitive tests.
Women who abstained from alcohol during follow-up had significantly worse cognitive performance compared with those with low alcohol consumption.
There are several possible explanations for the apparent cognitive benefits of moderate alcohol consumption noted in this study and others, Dr. Arntzen and colleagues note. For instance, studies have shown that light to moderate alcohol intake may protect against ischemic stroke and magnetic resonance imaging–detected white matter lesions, which suggests that the protective effects of alcohol on cognitive function are partly effected through vascular mechanisms, they write.
Flavonoids in red wine may reduce oxidative stress, which is thought to play a role in Alzheimer's disease by the formation in the brain of amyloid-beta protein, abnormal tau protein, and DNA damage in neurons. In the Canadian Study of Health and Aging, the team notes, moderate intake of wine, but not beer or spirits, halved the risk for Alzheimer's disease after 5 years of follow-up.
Clinically, neurologists and psychiatrists are much more used to dealing with the effects of excessive alcohol use.
"There is a lot of public health evidence on the benefits to both heart and brain of light to moderate alcohol use," Dr. Ganguli told Medscape Medical News. However, "clinically, neurologists and psychiatrists are much more used to dealing with the effects of excessive alcohol use. In addition, alcohol can interact with many of the medications we prescribe, so by and large, we are not in the habit of recommending alcohol use in, for example, the way we recommend physical exercise."
Nonetheless, Dr. Ganguli said, "there is clearly a consistent signal here that should be followed up."
Dr. Arntzen's team notes in their report that an upper limit for the positive effect of wine intake could not be determined because of the very few participants in this study with high alcohol intakes.
A lack of information on baseline cognitive function made it impossible to assess how alcohol intake may influence cognitive decline. Limited available information on socioeconomic status and possible differences in unmeasured lifestyle variables between drinkers and nondrinkers are also limitations.
"Because of cohort effects, results may not apply to younger generations with other drinking habits," they add.
The study authors and Dr. Ganguli have disclosed no relevant financial relationships.
Acta Neurol Scand. 2010;122:23-29.