Cardiovascular Risk Factors - Risk Factors For Alzheimers Disease: Alzheimers

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Cardiovascular risk factors

Many studies show that physiological conditions that harm the heart and blood vessels also increase the risk of Alzheimer's disease and vascular cognitive impairment. These include high blood pressure, high cholesterol, obesity, and smoking, which all increase the risk of stroke, a direct cause of vascular cognitive impairment. But such risk factors may also indirectly lead to Alzheimer's disease by other means.

High cholesterol

People with high total cholesterol face increased odds of Alzheimer's disease later in life. A desirable level is less than 200 milligrams of cholesterol per deciliter (mg/dL) of blood. People with cholesterol readings of more than 251 mg/dL during middle age were twice as likely as people with lower cholesterol levels to develop Alzheimer's within 21 years, according to a 2005 study of 1,449 adults published in Archives of Neurology. There is some evidence that statins, a commonly prescribed class of cholesterol-lowering drugs, may reduce the risk of Alzheimer's disease (see "Statins").

Hypertension

Several studies show that people with high blood pressure are at increased risk of Alzheimer's disease. Blood pressure is considered high if systolic pressure (the first number in a blood pressure reading, taken during the heart's pumping phase) is 140 millimeters of mercury (mm Hg) or more, or if diastolic blood pressure (the second number in the reading, taken during the heart's resting phase) is 90 mm Hg or more. Treating high blood pressure may help prevent Alzheimer's. A 2006 study in Archives of Neurology, which included 3,300 people over age 65, found that those taking any blood pressure medication had a 36% lower risk of developing Alzheimer's disease than those who took none. The greatest risk reduction was in people who were taking diuretics.

Obesity

Research points to excess weight as a risk factor for Alzheimer's disease and other dementias. People who were obese in middle age were nearly two and a half times as likely to eventually be diagnosed with Alzheimer's disease or another dementia as were people whose weight was normal, according to a 2005 Swedish study in Archives of Neurology. Similar findings, based on an American study involving 9,000 people, were reported at a 2006 meeting of the American Academy of Neurology. Both the Swedish and American teams found that obesity roughly doubled the risk of dementia even when people did not have other risk factors, such as high blood pressure and high cholesterol, that can also increase the likelihood of dementia.

Smoking

Smoking is a risk factor for cardiovascular disease, so it makes sense that it would also make you vulnerable to Alzheimer's disease and other dementias. Several studies have found a link. A 2005 study published in Neurology, which examined a number of vascular risk factors, found that smoking and diabetes were the ones most strongly linked with developing Alzheimer's disease. Another study, published in Neuroepidemiology in 2006, found that smokers were more than three times as likely to develop Alzheimer's as people who never smoked. However, it is unclear how much people who quit smoking reduce their risk of Alzheimer's.

Homocysteine

A number of studies have concluded that people with high blood levels of the amino acid homocysteine are at increased risk for heart disease and stroke, so researchers also investigated whether there is a link between homocysteine and dementia. So far, the results have been mixed. A 2002 study published in the New England Journal of Medicine concluded that people who had high homocysteine levels were more likely to develop Alzheimer's disease than those with low levels. In 2005, a study published in Neurology found a significant correlation between high homocysteine and beta-amyloid protein in blood, a possible risk factor for Alzheimer's disease. However, the study found no significant difference in homocysteine levels among people with Alzheimer's disease and a control group. More research is needed to clarify the relationship between homocysteine and Alzheimer's disease.

Homocysteine forms when the body breaks down protein. Then it either accumulates in the body or is recycled with the help of B vitamins. When individuals don't get enough of three B vitamins — folic acid, B₆, and B₁₂ — homocysteine levels rise.

Thus far, however, no evidence exists that lowering homocysteine will help stave off Alzheimer's disease — or heart disease, for that matter. Even so, it's important to get enough folic acid and vitamins B₆ and B₁₂, as these vitamins perform a number of vital roles in the body. Many breakfast cereals, pastas, and other grains are now fortified with B vitamins. Green leafy vegetables, citrus fruits and juices, bananas, and dry beans are good choices, too. Also consider taking a multivitamin with 400 micrograms of folic acid, 100 milligrams of vitamin B₆, and 100 micrograms of B₁₂.

Last updated:	January 23, 2007