Can drinking alcohol prevent dementia?

By David Liu

A new study presented on July 13 at the Alzheimer's Association 2009 International Conference on Alzheimer's Disease (ICAD) in Vienna suggests that drinking alcohol in moderation may reduce risk of dementia in older adults.

The study showed that individuals who were healthy at the beginning of the study and drank eight to 14 drinks each week during the six-year follow-up had their risk of dementia reduced by 37 percent.

For the study, Kaycee Sink, M.D., M.A.S of Wake Forest University School of Medicine and colleagues examined and interviewed 3,069 men and women aged 75 or older for their drinking habits. Most of the participants had no memory or thinking problems when they entered the study.

The researchers categorized the participants as abstainers (non-drinkers), light drinkers (one to seven drinks per week), moderate drinkers (eight to 14 drinks per week), or heavy drinkers (more than 14 drinks per week). All types of alcohol including beer, wine, and liquor were considered.

Those who drank any type of alcohol moderately were 37 percent less likely to have dementia than those who did not drink at all or abstainers.

However, those who had cognitive impairment at the start of the study and drank any amount of alcohol experienced faster rates of cognitive decline.  

In addition, heavy drinkers or those who drank more than 14 drinks per week were almost twice as likely to acquire dementia during the study compared to non-drinkers with mild cognitive impairment, the researchers reported.
  
The study did not consider participants' drinking habits prior to the study.

Wake Forest University Baptist Medical Center published a press release saying that "it is unclear whether an abstainer who begins drinking moderately in his/her 70s will experience the same benefit or if the benefit is associated with a long pattern of moderate alcohol intake that continues on into old age." 

Previous studies have suggested that drinking alcohol may reduce risk of dementia like Alzheimer's disease.

Anstey K. J. and colleagues from Australian National University in Canberra, Australia published on the July 17, 2009 issue of American Journal of Geriatrics and Psychiatry a review article suggesting that "alcohol drinkers in late life have reduced risk of dementia."

Anstey and colleagues reviewed 15 prospective studies that lasted 2 to 9 years. They meta-analyzed data from14,646 women and men for Alzheimer's disease, and data from 10,225 individuals for vascular dementia and 11,875 for any type of dementia.

Those who drank lightly or moderately were 28 percent less likely to acquire Alzheimer's disease, 25 percent less likely to develop vascular dementia and 26 percent less likely to have any dementia than non-drinkers.

The risk of Alzheimer's was 34 percent less for drinkers and the risk of any dementia was 47 percent less for drinkers than non-drinkers. But the drinking did not seem to change the risk of cognitive decline.

One of Anstey's findings was inconsistent with what was found by Sink and colleagues. That is, Anstey and team did not find heavy drinkers were at an increased risk of any dementia compared with nondrinkers. But they said their finding may result from sampling bias.

The researchers acknowledged that "it is unclear whether this reflects selection effects in cohort studies commencing in late life, a protective effect of alcohol consumption throughout adulthood, or a specific benefit of alcohol in late life."

Those who are intrigued by what Sink’s findings may need to know that alcoholic beverages are officially recognized by the U.S. government as carcinogens, that is, drinking alcohol increases cancer risk. The adverse effects could be more significant in those who lack the enzyme responsible for metabolism of alcohol.

The good news is that people do not have to drink alcohol to reduce their risk of dementia. Studies have shown that certain dietary habits can help reduce the risk while other patterns may increase it.

One study found that high intake of meat, butter, high-fat dairy products, eggs, and refined sugar was associated with high risk of Alzheimer's disease while high intake of grains and vegetables was linked to a lower risk.

That study was conducted by Gustaw-Rothenberg K from the Case Western Reserve University in Cleveland Ohio and published in the April 2009 issue of International journal of environmental research and public health.