TUESDAY, May 10, 2022 (HealthDay News) — Certain lifestyle factors can influence your risk of dementia, and a new study points to the top threats Americans face these days: obesity, physical inactivity and a lack of a high school diploma.
Researchers have found that only in the past decade has there been a shift in the most important modifiable risk factors for dementia in the United States. In 2011, the big three were physical inactivity, depression, and smoking.
Today, lack of exercise is still among the top three, but the other points have been replaced by middle-aged obesity and low education levels (no high school graduation).
At the same time, the study found that the top three are not one-size-fits-all: The main modifiable risk factors for dementia vary somewhat according to race and ethnicity.
Obesity was the number one factor among white, black, and Native American adults, while lack of exercise was the biggest threat to Asian Americans. Meanwhile, low educational attainment among Hispanic Americans has emerged as the largest modifiable risk factor.
“Our results suggest that people may be able to reduce their risk of developing Alzheimer’s disease and [other types of] Researcher Deborah Barnes, MD, associate professor of psychiatry at the University of California, San Francisco, said dementia is helped by engaging in a healthy lifestyle.
The biggest risk factor for Alzheimer’s disease and other forms of dementia is age, which people obviously cannot change. Genetic susceptibility is another major player. People who carry a genetic variant called APOE4, for example, have a higher likelihood of developing Alzheimer’s disease than non-carriers.
It’s estimated that around 40% of dementia cases worldwide can be attributed to modifiable risk factors, said Rebecca Edelmayer, senior director of scientific engagement at the Alzheimer’s Association.
These include the top three centers found in this study, as well as factors such as high blood pressure, diabetes, excessive drinking and hearing loss.
Edelmayer, who was not involved in the new research, said the reasons for these links aren’t entirely clear. But cardiovascular health is thought to be one pathway. Obesity, high blood pressure, diabetes, smoking, and a sedentary lifestyle can damage the blood vessels that nourish not only the heart, but the brain.
“The strongest data we have is that what’s good for your heart is good for your brain,” Edelmayer said.
As for education, the researchers think this may be helped by a so-called “cognitive reserve” hypothesis: people with higher education may be better equipped to withstand the pathological brain changes seen in dementia, preserving their memory and thinking abilities for longer.
The current results were published on May 9 in Gamma Neurology. It is based on more than 378,000 American adults who participated in an annual government health survey.
Overall, researchers estimate that 37% of dementia cases nationwide are linked to any of the eight modifiable risk factors: middle-aged obesity, inactivity, low educational attainment, depression, high blood pressure, diabetes, smoking, and hearing loss.
One reason, Barnes said, is sheer prevalence. Obesity has become more common over the past decade, so it is contributing to more cases of dementia.
Meanwhile, recent studies have indicated that the link between low levels of education and dementia is stronger than previously thought. Therefore, researchers estimate that this factor contributes to the increased incidence of dementia among Americans.
But the relative importance of those factors among different groups of Americans varies. Besides the differences observed between racial/ethnic groups, men and women showed some variance. Modifiable risk factors played a greater role in the risk of dementia in men – 36% of cases were linked to these factors, compared to 30% among women.
Depression was also a larger contributor for women than for men. Among women, nearly 11% of dementia cases can be linked to a lifelong history of depression, according to co-author Dr. Rosh Nyango, of the University of California, Los Angeles School of Public Health.
Nearly a quarter of the women in the study said they had been diagnosed with depression at some point.
Edelmayer said the research is now moving beyond finding associations to testing ways to reduce dementia risk.
“We think that adopting a set of healthy behaviors may be more effective,” Edelmayer said.
The Alzheimer’s Association is funding a trial called US POINTER, which tests this combination approach among older adults at risk of developing dementia. Lifestyle measures include exercise, mental stimulation activities, and better control of high blood pressure and diabetes.
Edelmayer said it’s critical for the studies to recruit people of color, who have historically been underrepresented in medical research. As this study shows, it notes, the most important modifiable risk factors for dementia vary among different groups of Americans.
The Alzheimer’s Association offers tips on protecting brain health.
SOURCES: Deborah Barnes, Ph.D., professor of psychiatry, University of California, San Francisco; Rosh Nyanoghu, MD, PhD, assistant professor, epidemiology, Fielding School of Public Health, University of California, Los Angeles; Rebecca Edelmayer, Ph.D., Senior Director, Scientific Engagement, Alzheimer’s Association, Chicago; gamma neurology, May 9, 2022, online