ORLANDO, Nov. 11 -- People should start paying attention to their blood levels of cholesterol early in life, according to a study that finds cholesterol levels during middle age are more strongly tied to heart disease risk than cholesterol levels during older-age.
Reporting the study at the American Heart Association's 70th Scientific Sessions, Robert D. Abbott, Ph.D., a professor of biostatistics and statistics at the University of Virginia in Charlottesville, says the research findings suggest that individuals who have high cholesterol when they are in middle adulthood may continue to have a high risk of heart disease in spite of declines in cholesterol that may occur spontaneously with age. Researchers have often thought that cholesterol declines as people age beyond 65 years.
"The risk of heart disease in later life seems often to be driven by cholesterol levels in middle adulthood," he says. "If a person can get their cholesterol down early in life and keeps it down, cholesterol may becomes less of an issue later in life. But if the individual has a history of elevated cholesterol and other risk factors, low cholesterol levels in older age does not make everything right."
Abbott and lead author Amy A. Hakim compared the risk of heart attack and death from heart disease in 1,170 men enrolled in the Honolulu Heart Program, an ongoing study of health behaviors and heart disease. The men were between the ages of 61 and 81 and free of heart disease at the beginning of evaluation, but the authors also had access to cholesterol measurements that were taken 10 years earlier.
Among men who were classified as having the greatest declines in their cholesterol (about 20 percent of the study sample), the risk of heart disease was four times greater than it was for men who were classified as having the greatest increases in cholesterol (another 20 percent of the study sample). But the catch is, Abbott explains, "men whose cholesterol dropped the most, began with cholesterol levels 10 years earlier that were excessively high, while those who had an increase in cholesterol began with cholesterol levels that were low, and even though cholesterol increased, it continued to remain low." It turns out that among men who had the largest increases in cholesterol, all had levels below 235 mg/dl in middle adulthood. After 10 years, 75 percent continued to have levels below this value. In contrast, for those whose cholesterol levels declined, half had cholesterol levels in middle adulthood that were well above 235 mg/dl. In this later group, average cholesterol levels dropped from 236 to 191 mg/dl over 10 years. A desirable cholesterol level is less than 200 mg/dl. High cholesterol is above 240 mg/dl.
The authors of the report conclude that when assessing low cholesterol in older individuals, it may be important to consider past histories of elevated cholesterol levels as well. Abbott further notes that, "as we age, factors contributing to heart disease seem to increase in numbers, and while prevention may continue to include control of cholesterol, it also means that greater attention needs to be focused on a collection of other preventive measures that may include increasing physical activity, improving nutrition and increasing our understanding of aging and health."
Co-authors are Cecil M. Burchfield, Dan S. Sharp, Katsuhiko Yano, Beatriz L. Rodriguez, J. David Curb, Honolulu Heart Program, Honolulu HI.
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