Majority of Alzheimer’s, dementia cases linked to 8 modifiable risk factors
A cross-sectional analysis showed that eight modifiable risk factors were associated with more than one in three cases of Alzheimer’s disease and related dementia in the US.
As Roach reports, eight risk factors – midlife obesity, midlife hypertension, physical inactivity, depression, smoking, low education, diabetes and hearing loss – accounted for 36.9% (95% CI 36.5–37.3) of Alzheimer’s and dementia cases. were connected. Niyango, MD, PhD, of the University of California Los Angeles, and Deborah Barnes, PhD, MPH, of the University of California San Francisco, and co-authors.
Of note, risk factors vary by gender, race and ethnicity, they wrote. JAMA Neurology,
The factors most prominently associated with Alzheimer’s and dementia were middle-aged obesity at 17.7% (95% CI 17.5–18.0); physical inactivity, at 11.8% (95% CI 11.7–11.9); and lower educational attainment, at 11.7% (95% CI 11.5–12.0).
“We published a similar study 10 years ago, and the most significant risk factors were physical inactivity, depression, and smoking,” Barnes said. medpages today,
“Today, the top three risk factors are middle-age obesity, physical inactivity, and low education,” she observed. “This is important because it suggests that the increasing number of people who are obese in the US could have a major long-term impact on dementia rates.”
“Our results also highlight the importance of ensuring that everyone in our country has an adequate education,” Barnes said. “COVID-19 had a devastating effect on education and graduation rates and it will be important to help those students catch up. This is especially true among Hispanic individuals, where low education is the biggest risk factor.”
Because there is no effective cure for Alzheimer’s and dementia, prevention is very important, Nianogo stressed. They suggested that risk reduction strategies may be more effective if they target high prevalence risk factors.
“Understanding which risk factors play a role in accelerating cognitive decline can help providers and individuals be proactive in addressing these risk factors early in their lifetime,” Nianogo said. medpages today, “We also wanted to understand what this meant for different subpopulations defined by sex and race and ethnicity, as this could be important for designing tailored and targeted interventions.”
About two-thirds of people with Alzheimer’s and dementia in the US are women. Compared to white older adults, black older adults are twice as likely to develop Alzheimer’s and dementia, and 1.5 times as likely among Hispanic older adults.
Nianogo and Barnes note that risk reduction may provide an important public health and prevention opportunity to help offset the projected increase in dementia prevalence.
For this study, researchers collected risk factor prevalence information from 378,615 participants in the 2018 CDC Behavioral Risk Factor Monitoring System and derived relative risks for each factor from recent meta-analyses.
In the study sample, 171,161 people (weighing 48.7%) were men and 134,693 people (weighing 21.1%) were 65 and older. Self-reported race and ethnicity data showed that 6,671 participants (weighted 0.9%) were American Indian and Alaska Native; 8,043 (weighted 5.1%) were Asian; 29,956 (weighted 11.7%) were black; 28,042 (weighted 16.0%) were Hispanic; and 294,394 (weighted 64.3%) were white.
For each of the eight modifiable risk factors, the population-attributable risk was:
- Deafness: 2.3%
- Current smoking: 6.0%
- Diabetes: 7.3%
- Depression: 8.5%
- Mid-life hypertension: 8.8%
- Low education: 11.7%
- Physical inactivity: 11.8%
- Middle age obesity: 17.7%
Midlife hypertension and midlife obesity were the most prevalent risk factors among all participants, but prevalence varied by race and ethnicity. Midlife obesity was more prevalent in American Indian and Alaska Native, Black and Hispanic populations; Low education was more prevalent among Hispanic individuals.
The associations with Alzheimer’s and dementia risk also differed by race and ethnicity. In Black (21.7%), American Indian and Alaska Native (20.3%), and White (17.3%) populations, midlife obesity showed the strongest association with Alzheimer’s and dementia. Among Hispanic individuals, low educational attainment had the strongest tie (26.5%), whereas among Asian participants, physical inactivity was at the top of the list (9.5%).
The combined population-attributable risks were higher in men (35.9%) than in women (30.1%). The risks associated with depression were higher in women (10.5%) than in men (6.4%).
The researchers said the findings suggest that the most prominently modifiable risk factors associated with Alzheimer’s and dementia have changed over the past decade and differ by gender, race and ethnicity.
“It is important to note that these findings were based mostly on observational studies,” Nianogo pointed out.
“While they may reflect what is actually happening, they may also reflect the effect of other factors that have not been included in our study,” he acknowledged. “More rigorous study designs are needed to shed more light on this important issue.”
Disclosures
The study was supported by the California Department of Public Health’s Alzheimer’s Disease Program through the 2019 California Budget Act.
Nianogo, Barnes and co-authors did not report any disclosures.
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