Aug. 4, 2009 -- Adults with even moderately elevated cholesterol in their early to mid-40s appear to have an increased risk for Alzheimer's disease and related dementias decades later, a new study shows.
Researchers followed more than 9,800 people for four decades in one of the largest and longest age-related dementia trials ever conducted.
"People tend to think of the brain and the heart as totally separate, but they are not," study co-author Rachel A. Whitmer, PhD of Kaiser Permanente Division of Research in Oakland, Calif., tells WebMD. "We are learning that what is good for the heart is also good for the brain -- and that midlife is not too soon to be thinking about risk factors for dementia."
Cholesterol and Alzheimer's Disease
The study included 9,844 northern California residents enrolled in the same health insurance plan throughout the study.
Total cholesterol in the high range at study entry was associated with a 66% increase in Alzheimer's risk, while having borderline high cholesterol raised the risk for vascular dementia by 52%.
According to current guidelines, total cholesterol of 240 or higher is considered high, and a cholesterol of 200 to 239 is considered borderline high.
The researchers did not have information on HDL "good" and LDL "bad" cholesterol because the significance of these different types of lipids was not widely understood four decades ago.
But it is safe to assume that most people whose total cholesterol was high had high levels of bad cholesterol because about two-thirds of total cholesterol reflects LDL, Whitmer says.
Good for Heart, Good for Brain
The study, conducted by researchers with Kaiser and Finland's University of Kuopio, is one of the first to examine risk for vascular dementia, a group of dementia syndromes associated with reduced blood supply to the brain.
Lead author Alina Solomon, MD, of the University of Kuopio tells WebMD that the study adds to the growing evidence that controlling heart disease risk factors like cholesterol, blood pressure, diabetes, and weight in midlife can protect the brain in old age.
"Keeping your weight down, eating right, and getting regular exercise can keep your heart healthy as you age, and it may also keep your brain sharp," she says.
Alzheimer's Association Chief Medical and Scientific Officer William H. Thies, PhD, agrees that it is increasingly clear that lifestyle influences risk, even among people who have a genetic predisposition for developing late-life dementias.
"We can't really say how much of risk is lifestyle and how much is genetic," he says. "We know that most patients with Alzheimer's also have vascular disease and that the risk factors for vascular disease are modifiable with lifestyle."
Making Changes to Lower Risk
Computer specialist James Pitman, 44, has gotten the message and is making lifestyle changes to bring his high cholesterol down in hopes of reducing his risk for heart disease, diabetes, and dementia later in life.
The Oakland, Calif., resident, who has a family history of diabetes and Alzheimer's disease, has lowered his total cholesterol from 280 to 260 by eating better and revamping his exercise routine. He tells WebMD that he hopes to lower his numbers more by making additional changes.
"I didn't exactly win the genetic lottery, so I will probably have to go on drugs eventually to lower my cholesterol," he says. "But I am going to do all I can with diet and exercise."