Researchers in Spain examining the relationship between smoking, alcohol and Alzheimer's disease have found that the risk of the degenerative brain disease is lowest among those who drink responsibly and avoid tobacco. But their conclusions are far from comprehensive.
The team from the Department of Preventive Medicine and Public Health at the University of Valencia say the results are strongest in women, and that choice of beverage doesn't appear to matter. But the links between smoking and Alzheimer's, however, aren't as clear.
For the study, the researchers gathered data from 422 elderly residents living in and around Valencia, 176 of whom had been diagnosed with Alzheimer's. The researchers asked the 246 subjects in the control group to complete questionnaires on lifetime exposure to alcohol and tobacco. Relatives completed the survey for the Alzheimer's patients.
The results, published in the May issue of the Journal of Alzheimer's Disease, report that the women who drank light to moderate amounts of alcohol, about one to two drinks a day, and didn't smoke, had a 52 percent lower risk of Alzheimer's disease than those who abstain from both alcohol and tobacco. For men, the risk was 20 percent less.
"Interactive effects of smoking and drinking are supported by the fact that both alcohol and tobacco affect brain neuronal receptors," explained lead researcher Ana Garcia in statement. She added that the results show the "need to consider interactions between tobacco and alcohol consumption, as well as interactions with gender, when assessing the effects of smoking and/or drinking on the risk of Alzheimer's."
But, the research was not as clear on other factors. For example, women in the study who smoked, but didn't drink, had no clinically greater risk of Alzheimer's disease than women who abstained from both.
So smoking increases the risk of Alzheimer's in drinkers, but not in nondrinkers? The scientists were unable to provide an explanation. They concluded that more research is needed.
The researchers expected red wine to show a greater protective effect, a result observed in earlier research. "It has been proposed that [the antioxidant] resveratrol, found in wine but not in other alcoholic beverages, could be responsible," for those earlier results, the authors wrote. But the study data found no significant difference between subjects who drank beer, wine or liquor.