July 12, 2006

Dutch Treat

The Framingham Study is probably the most famous long-term medical study ever designed. Founded in 1948 to identify risk factors for heart disease, it began by following 5209 people from the city of Framingham, Massachusetts. It was so successful, definitively showing the importance of smoking, high blood pressure, cholesterol, diabetes, and inactivity in causing coronary heart disease, that a second group of about 5000 people were added in 1971—the children of the first group, along with their spouses. Less well-known, but also teeming with useful insights is another epidemiological study, this one conducted in a suburb of Rotterdam, Holland (A. Hofman, P. deJong, C. van Duijn et al, “Epidemiology of Neurologic Diseases in Elderly People: What Did We Learn from the Rotterdam Study?” Lancet Neurology 2006; 5: 545-50).

The Rotterdam Study has been following a group of men and women since 1990 and is concerned with finding potentially modifiable factors that put older people at risk of debilitating chronic disease. It recruited just under 8000 people over the age of 55, with the oldest participant age 106. Each study member was put through a 2-hour interview at home and a 5-hour battery of tests. On average the examinations were repeated every 3 years, focusing on the heart, the blood vessels, eyes, skeleton, and brain.

Just as the Framingham Study was particularly concerned with heart disease, the Rotterdam Study was especially interested in understanding more about neurologic disease (such as dementia and Parkinson’s disease), visual problems (mainly macular degeneration), and problems with mobility (arising principally from osteoporosis and fractures). The investigators found that by age 85, about 20% of the study group had dementia, and by age 95, the percentage had risen to over 40%. But they also found that the same factors that are associated with heart disease—high blood pressure, cholesterol, and cigarette smoking, along with diabetes—are associated with dementia. And those factors appeared to be important not just for the development of “vascular dementia,” or the dementia arising from multiple strokes, but also for producing Alzheimer’s disease.

The good news from Rotterdam, confirming earlier findings from smaller studies, is that we may be able to prevent dementia in the elderly, or at least delay its clinical manifestations, by treating high blood pressure, lowering cholesterol, avoiding smoking, and preventing or treating diabetes. It remains to be demonstrated that actually doing all these things will in fact make a difference, but it seems well worth a try.

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