Cardiovascular disease & Alzheimer's disease.

One of the most intriguing discoveries about Alzheimer's disease in the last few years is that many of the risk factors for cardiovascular disease are also risk factors for Alzheimer's disease.

"It appears right now that almost everything that increases your risk of vascular disease in some fashion probably increases your risk for Alzheimer's disease," says William H. Thies, PhD, vice president of medical and scientific affairs at the Chicago-based Alzheimer's Association. These risk factors include high blood pressure, being overweight or obese, high cholesterol levels, high levels of homocysteine (an amino acid in the blood) and a sedentary lifestyle.

Although researchers are still exploring the reasons behind the link, they have several theories. One is that having an intact vascular, or blood, system within the brain helps maximize the brain's potential, says Dr. Thies. If blood flow is restricted because of a buildup of plaque or clots in blood vessels, or if blood vessels become too stiff to enable the smooth flow of blood, less oxygen gets to the brain and fewer waste products leave the brain, he notes.

In fact, he says, back in the 1960s all forms of dementia were referred to as "hardening of the arteries." Then, with a better understanding of the processes in the brain that led to Alzheimer's disease, the diagnosis shifted in the 1970s and 1980s to Alzheimer's disease. Today, he says, it's most likely that there are two primary causes of dementia: an Alzheimer's disease type "pathology," represented by the neurofibrillary tangles and senile plaques of the disease, and vascular dementia, resulting from significant changes in blood vessels in the brain. "Probably everyone over 80 who is showing some signs of dementia shows some combination of both types," he said.

Another intriguing theory suggests that cholesterol plays a role in the development of the amyloid plaques that are a hallmark of the disease. "In animals, we find that they make extra plaque if you feed them a cholesterol-rich diet," Dr. Thies says. Take them off the diet and/or put them on a cholesterol-lowering drug like a statin, and they build up less plaque. That may help explain studies that find that people taking statins like atorvastatin or lovastatin seem to have a lower risk of developing Alzheimer's disease.

"I suspect both theories are going to end up being true and when we get the total picture it will be a combination of events that contribute to Alzheimer's disease," he says. "But it does appear that having a healthy blood vessel structure in the brain is really a big help to the brain."

That means it's important to "know your numbers," says Dr. Thies, including blood pressure, blood sugar and cholesterol levels, and to work to maintain healthy ranges of those numbers. (For more on lifestyle changes to reduce your risk of Alzheimer's disease, see page 8.)

Paying attention to cardiovascular risk factors may also influence the course of the disease once someone is diagnosed, says Laurel Coleman, MD, a member of the Alzheimer's Association's board of directors. "If I have a patient with early Alzheimer's disease, I can't reverse the amyloid in their brain, but I know if their blood pressure or cholesterol is very bad that it is probably going to accelerate their decline," she says.

In fact, improving the cardiovascular health of Americans could have a big impact in delaying the onset of Alzheimer's disease, notes William W. Pendlebury, MD, medical director of the Memory Center and Elder Care Services at the University of Vermont in Burlington. That, in turn, could have a major impact on the way the disease affects families and the health care system.

Right now, he notes, the median age of those stricken with Alzheimer's is 73. ("Median" means half the people who develop it are older than 73 and half who develop it are younger.) "If you pushed that number back by five years, to age 78, for example, you'd reduce the prevalence of the disease by 50 percent," he says.

RELATED ARTICLE: 10 Warning Signs of Alzheimer's Disease

1. Memory loss

2. Difficulty performing familiar tasks

3. Problems with language

4. Disorientation to time and place

5. Poor or decreased judgment

6. Problems with abstract thinking

7. Misplacing things

8. Changes in mood or behavior

9. Changes in personality

10. Loss of initiative

Source: Alzheimer's Association