Page last updated: Wednesday, November 19, 2008
R. Curtis Ellison comments on new studies seeking the causes of Alzheimers disease and other types of dementia
One of the most dreaded outcomes associated with ageing is Alzheimer’s Disease and other types of dementia. Unfortunately, we know very little about what causes dementia. For a very small percentage of cases, especially those individuals who begin to show evidence of such a disorder at a younger age, a genetic linkage has been found. For the majority of cases, however, other than a previous stroke or serious head injury, underlying causes are not known.

While the detailed papers have not yet been published, there have been reports of two presentations at a recent scientific meeting of the American Academy of Neurology in Chicago that linked lifestyle factors to Alzheimer’s Disease. In addition, a recent publication related long-term risk of dementia with the consumption of beer, wine, and spirits. These three studies are commented upon below:

(1) A study from Florida (presented at the neurology meeting by Dr. Ranjan Duara) identified heavy drinking (defined in this study as an average of more than 28 g/day of alcohol, or between 2 and 3 typical drinks of 10 to 12 grams), heavy smoking (20 or more cigarettes/day), and a genetic factor (a specific form of apolipoprotein E, or ApoE) as increasing the risk of Alzheimer’s. People who were heavy drinkers, heavy smokers, and had the specific ApoE genotype were reported to develop Alzheimer’s about 8 years earlier than those with none of these factors.

Unfortunately, no data are yet available on the pattern of drinking of the subjects in this study. Thus, it is not known which subjects were binge drinkers (consuming all of their alcohol on one or two days per week) or were regular drinkers throughout the week. Most studies have shown that binge drinking is associated with more adverse health effects, while frequent, moderate intake has often been found to be associated with beneficial effects. Further, in the report of this presentation, the effects of more moderate drinking on the risk of dementia were not given. Until the paper is published, it will not be possible to judge if there were other associated lifestyle factors that may have “confounded” the reported relation.

(2) Another paper presented at the neurology meeting (by Dr. Alina Solomon of Finland and based on data from the large Kaiser Permanente health group in California) found that middle-aged men and women with levels of blood cholesterol above 200 mg/dL, especially those with values of 250 or higher, had an increased risk of developing Alzheimer’s. A relation between high cholesterol has previously been seen in a number of other epidemiologic studies and has suggested to some that small degrees of atherosclerosis of the cerebral arteries (not enough to cause a recognizable stroke) may be a mechanism. Others suggest that the high levels of cholesterol are associated with higher degrees of inflammation, which may be the important factor. At this time, the reasons for the somewhat higher risk of dementia with higher cholesterol are not known.

(3) An important paper from Sweden (by Dr. Kirsten Mehlig and co-workers, recently published in the American Journal of Epidemiology) related alcohol intake to the subsequent development of dementia. In a long-term (34-year follow up) prospective study of women in Göteborg, Sweden, what was essentially the lifetime risk of dementia of the women was associated differently with wine consumption (a decrease in risk of dementia of 70%) and spirits consumption (an increase in dementia risk of about 50%); beer consumption had essentially no effect on the risk of dementia.

The authors concluded that the different associations by type of beverage suggest that the non-alcohol components in wine may be an important factor in lowering the risk of dementia, and some other studies have also suggested greater benefit from wine than from other beverages containing alcohol. While the investigators in the Swedish study adjusted for the usual risk factors for dementia, including education and social class, there is always the possibility that other lifestyle factors that were different between wine drinkers and spirits drinkers may have influenced the result.

Overall, these studies are beginning to identify some potential risk factors for dementia that, we hope, will lead to ways of preventing or reducing the risk of this dreaded disease.

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