American Heart Association meeting report:
DALLAS, Nov. 9 -- How many risk factors you have for heart disease and stroke may determine how well you think and remember, according a new study that links the combined effects of diabetes, cigarette smoking, high blood pressure and obesity to mental ability. The information was presented today at the American Heart Association's 71st Scientific Sessions.
"The more risk factors the more mental decline," says lead author of the study Merrill F. Elias, Ph.D., professor of psychology at the University of Maine in Orono and adjunct research professor of medicine and public health at the Boston University School of Medicine.
"We want people to function at the highest possible level and for the longest possible time," says Elias. "People are a national resource. Individuals are going to have a reduced quality of life if they cannot learn and remember." Previous studies have shown that high blood pressure and diabetes may impair thinking abilities, says Elias. But the new research by Elias and his colleagues identified two other risk factors, obesity and smoking, that increased a person's chance of mental decline.
Elias's group tested 1,799 volunteers in the Framingham Heart Study, which has tracked the cardiovascular health of a group of residents in a community near Boston for about 50 years. Between 1976 and 1978, the volunteers, age 55 to 85 years, took a series of eight neuropsychological tests designed to assess their thinking and memory abilities. Those scoring in the lowest 25 percent were considered to be "poor performers."
Researchers also assigned to each volunteer a number (0-4) representing how many risk factors for heart disease the individual had at the time of testing. "The study showed that the more risk factors for heart disease a person has, the greater the risk of developing memory and learning impairments," says Elias. After analyzing the total scores achieved on all eight tests, researchers found that people with one of four risk factors at the time of testing were, on average, 23 percent more likely to be poor performers than those with no risk factors. With each additional risk factor, the volunteers' risk of decreased mental function increased another 23 percent.
The researchers then narrowed their analysis to only the scores on three tests that assessed learning and memory, excluding those that measured attention, concentration or word fluency.
"Again, more risk factors for heart disease indicated a higher chance of mental decline. People with one risk factor averaged a 32 percent increased risk of mental decline over those with no risk factors and again this chance increased by about 32 percent with each additional risk factor.
"This tells us that treating these risk factors provides not only a payoff in terms of decreased risk of stroke and heart disease, but there may be an additional benefit by helping to prevent or slow down the mental decline that comes with aging," he says.
The findings held up when the team controlled statistically for age, education, occupation, gender, total cholesterol levels, alcohol use, and several forms of heart disease, including a previous heart attack.
The findings demonstrate that by counting the number of heart disease risk factors a person has, physicians could assess a person's risk for cognitive decline. Counseling from their doctor about the risk of cognitive decline might motivate people to control their blood pressure and diabetes, stop smoking, and lose weight, according to Elias.
Co-authors include: Penelope K. Elias, Ph.D.; Ralph B. D'Agostino, Ph.D.; Halit Silbershatz, Ph.D.; and Philip A. Wolf, M.D.