January 24, 2005
High cholesterol, high blood pressure, diabetes, and smoking -- long considered serious risk factors for heart disease -- may also increase your long-term risk for Alzheimer's, a new study of nearly 9,000 Californians shows. Middle-aged men and women who had one or more of these risk factors during their early 40s were much more likely to develop Alzheimer's disease and other forms of dementia years down the road.
Researchers found that having any one of these risk factors in your early 40s increases your risk of dementia in later life by some 20 to 40 percent. Having two or more, though, was especially hazardous to your long-term mental acuity. Compared to individuals who had none of these risk factors for heart disease, those with two of the factors were 70 percent more likely to be diagnosed with dementia in later life. Those with three were more than twice as likely to develop dementia. And those with all four were at 2.37 times greater risk.
This study is important because it looked at a large number of people and charted their progress over several decades, solidifying earlier evidence that what's good for the heart is good for the brain. "The real strength of our study is the large, multiethnic cohort of men and women, followed up for 27 years, all with equal access to medical care," said study author Rachel Whitmer, Ph.D., of Kaiser Permanente, a non-profit HMO in Oakland, California. Participants included men and women of various ethnic groups, including whites, blacks, and Asians. All belonged to an HMO and had equal access to doctors and medical care. The study appeared in the January 25, 2005 issue of Neurology, the scientific journal of the American Academy of Neurology.
Here's how the individual risk factors broke down:
People who had diabetes in their middle years were at highest risk of developing Alzheimer's disease later in life. Diabetes increased the risk by 46 percent. Other studies indicate that those who develop diabetes late in life are also at increased risk of developing dementia. Doctors believe this may occur because diabetes damages blood vessels throughout the body, including those that feed the brain. Additional studies are needed to determine whether proper treatment and control of blood sugar throughout middle age and beyond can lower the risk of Alzheimer's.
Those with high cholesterol levels in their mid-years were 42 percent more likely to develop Alzheimer's as seniors. Doctors suspect that high cholesterol may lead to high levels of beta-amyloid, the toxic substance that builds up in the brains of those with Alzheimer's, killing off healthy brain cells. Other studies suggest that taking medications such as statin drugs that lower cholesterol may help to keep the memory intact, though more research into these medicines is needed.
High Blood Pressure
Men and women who had high blood pressure in their forties were 24 percent more likely to develop dementia later in life. Recent research have found that treating high blood pressure as we age may lower the risk of developing memory problems and dementia.
Research on the effects of smoking on Alzheimer's disease have been mixed. In this study, middle-aged smokers were 26 percent more likely to develop dementia with age. Some research suggests that the nicotine in tobacco smoke may actually lower the risk of Alzheimer's, because nicotine may help to stem the development of plaques that accumulate in the brains of those with the disease. However, other population studies suggest that smoking increases the risk of Alzheimer's and other forms of dementia.
Experts are hopeful that a sound diet, lots of exercise, other healthy lifestyle measures, and proper medical treatment -- all good for the heart -- may help to protect against Alzheimer's disease as well. This and other studies suggest that may be so. Alzheimer's, however, is a complex disease with genetic and various environmental factors all playing a role. No one measure can guarantee you'll stay sharp into old age, but at the least, a healthy lifestyle may help.
For more on the risk factors for Alzheimer's disease and ways you might help prevent it, visit www.ALZinfo.org, the Alzheimer's Information Site, for regular news updates on Wellness & Prevention.
R.A. Whitmer, Ph.D., S. Sidney, M.D., J. Selby, M.D., et al: "Midlife Cardiovascular Risk Factors and Risk of Dementia in Late Life." Neurology 2005; 64, pages 277-281.