The No. 1 Modifiable Risk Factor for Alzheimer’s Disease

August 24, 2022

Many factors help explain why some people develop Alzheimer’s disease. The genes you inherit and advancing age are among the most important risk factors for Alzheimer’s, and these factors cannot be controlled. But other risk factors, which account for about a third of cases, can in many cases be modified by adopting healthier habits, including eating a heart-healthy diet and getting regular exercise. 

As the population grows older, the number of Alzheimer’s cases in coming decades is expected to increase. Alzheimer’s disease, which accounts for 60 percent to 80 percent of all dementia cases, is the leading cause of disability in older adults.

Researchers continue to look for clues to better understand the underlying cases of Alzheimer’s, and to find more effective treatments that can modify the course of the disease. In the absence of disease-modifying treatments, taking lifestyle steps to reduce risk can be an important for helping to curb Alzheimer’s onset.

What’s the most important controllable risk factor for Alzheimer’s disease? Being obese in middle age, according to a new analysis of 378,615 Americans.

The analysis looked at data from the U.S. Behavioral Risk Factor Surveillance System, an annual survey that looks at health data over many years. Researchers evaluated the relative contribution of eight modifiable risk factors for Alzheimer’s disease and other forms of dementia: being physically inactive, being a current smoker, having depression, having low levels of formal education, having diabetes, being obese at midlife, midlife high blood pressure, and having impaired hearing.

Each of these eight risk factors were individually associated with about a third of the cases of Alzheimer’s overall, the researchers estimated. Midlife obesity was the most prominent risk factor for Alzheimer’s, followed by physical inactivity and low educational attainment.

Ten years ago, physical activity was the top risk factor for Alzheimer’s, followed by depression and smoking, the researchers calculated. As obesity rates have continued to increase among Americans in recent decades, it is not surprising that obesity is now the No. 1 modifiable risk factor for Alzheimer’s disease.

These eight risk factors were significant for both men and women, the researchers noted, though men were more likely to have modifiable risk factors than women. Midlife obesity was the most important modifiable risk factor among whites, Blacks, American Indians and Alaska Natives. Among Asian Americans, physical inactivity was most important, whereas for Hispanics, low education was most important.

By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University. 

Source: Roch A. Nianogo, MD, PhD1,2; Amy Rosenwohl-Mack, RN, MS3; Kristine Yaffe, MD; et al: “Risk Factors Associated With Alzheimer Disease and Related Dementias by Sex and Race and Ethnicity in the US.” JAMA Neurology, published online May 9, 2022


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