US Dementia Cases Projected to Double Within 40 Years


The number of US adults who will develop dementia each year is projected to increase from approximately 514,000 in 2020 to about 1 million in 2060, new research shows. 

In addition, the lifetime risk of developing dementia after age 55 is estimated at 42%. The research showed that the relative growth in dementia cases is particularly pronounced for Black adults. These new findings researchers say, “highlight the urgent need for policies that enhance healthy aging, with a focus on health equity.”

“The aging of the population means that the increased burden of cognitive decline and dementia, particularly among the oldest age group, is going to be significant, and we need to be prepared for it,” study investigator Josef Coresh, MD, PhD, director of the Optimal Aging Institute at NYU Grossman School of Medicine, New York City, told Medscape Medical News. 

He added that dementia may be preventable through such strategies as controlling vascular risk factors, treating sleep disorders, detecting and correcting hearing loss, managing mood disorders, and improving access to social support.

The findings were published online on January 13 in Nature Medicine.

Diverse Cohort, More Rigorous Methodology

Over the past century, the US population has aged substantially, resulting in a rise in late-life diseases. Once an uncommon condition, dementia now affects more than 6 million Americans.

The lifetime risk for dementia is a critical public health measure that can be used to raise awareness, enhance patient engagement in prevention, and inform policymaking, the investigators noted. 

The often-cited Framingham Heart Study estimates that 11%-14% of men and 19%-23% of women will develop dementia during their lifetime. But, as Coresh noted, these estimates were based on a predominantly White, relatively affluent, and well educated cohort, as well as limited means of determining dementia cases.

In contrast, this new study is based on a more diverse cohort and used more rigorous methodology, Coresh said. “It’s capturing the latest decade of risk, from age 85 to 95 years,” which is important because people are living longer, he added. 

The report analyzed data collected from 1987 to 2020 from 15,043 participants in the Atherosclerosis Risk in Communities (ARIC) study. Drawn from four US communities, these individuals were all dementia-free of dementia at age 55. One of the study sites was Jackson, Mississippi, where Black individuals comprise 82% of the population. 

Black individuals accounted for 26.9% of the total study population, 55.1% of participants were women, and 30.8% carried at least one copy of the apolipoprotein E (APOE) epsilon 4 allele (28.1% with one copy and 2.7% with two copies). 

Over the past three decades, study participants underwent clinical examinations, including cognitive testing, laboratory testing, and both in-person and telephone interviews. In addition to interviews, the ARIC study uses review of hospital records and death certificates to determine dementia, with cases adjudicated by a committee assisted by a computer algorithm.

Over a median follow-up of 23 years, 3252 new cases of dementia were identified.

At age 55, researchers estimated the lifetime risk for dementia (up to age 95) to be 42% (95% CI, 41-43). The cumulative incidence of dementia remained relatively low between 55 and 75 years of age (3.9%) but rose significantly beyond that.

Over a median follow-up of 23 years, there were 3252 incident cases of dementia.

The lifetime risk for dementia was higher in women (48%; 95% CI, 46-50) vs men (35%; 95% CI, 33-36) and in Black individuals (44%; 95% CI, 41-46) vs White individuals (41%; 95% CI, 40-43). Additionally, Black individuals experienced an earlier median age of dementia onset (79 years) compared with White individuals (82 years).

“By age 75, the risk is 3% in our White participants and 7% in our Black participants, so the racial difference is expressed early, and it stays to age 85 and then sort of closes and becomes smaller by age 95,” said Coresh.

Structural Racism

The racial disparity in dementia risk may reflect the impact of structural racism and socioeconomic inequality, including limited access to quality education and nutrition, said Coresh. Additionally, it could be influenced by poorer access to healthcare and a higher prevalence of vascular risk factors, such as hypertension and diabetes, he added.

“People who were born in the South a long time ago may not have had the same opportunities as people in other areas and of other races and ethnicities.”

The substantially higher risk among women is thought to reflect women’s longer life expectancy.

Adults with two copies of the APOE epsilon 4 allele had a higher lifetime risk for dementia (59%; 95% CI, 53-65) compared with those with one copy (48%; 95% CI, 45-50) and those with no copies (39%; 95% CI, 37-40). Dementia also occurred earlier in APOE epsilon 4 carriers (median age, 79 years in those with two copies, 81 years in those with one copy, and 82 years in those with no copies).

Applying the lifetime risk estimates to US Census population projections, the researchers predict the annual number of incident dementia cases will increase from about 514,000 in 2020 to 1 million in 2060. The number of individuals who will develop dementia each year is expected to nearly double among White individuals and triple among their Black counterparts.

These findings highlight the importance of addressing the growing number of Baby Boomers transitioning into the oldest age group, Coresh noted. As more individuals live into their 80s and beyond, the medical community must focus on managing early symptoms and implementing effective prevention strategies, he added.

Such strategies should include managing risk factors, such as social isolation, disordered sleep, mood issues, poor cardiovascular health, and uncorrected hearing loss, he said. As it stands, research suggests only about 20% of US adults meet recommended lifestyle and cardiovascular health targets, and only 30% of older adults with hearing loss are using a hearing aid.

Dementia before age 75 may be underestimated in the study because up until this age, dementia was ascertained retrospectively with phone interviews and review of hospital and death records. 

Other limitations of the study include the lack of external validation of the results, limited generalizability of the projections to the entire US population, and exclusion of racial groups other than White and Black from the analysis. 

A Crisis in the Making

Commenting for Medscape Medical News, Maria C. Carrillo, PhD, chief science officer and medical affairs lead for the Alzheimer’s Association, said the new findings reinforce what the Alzheimer’s Association has long emphasized: that the risk and prevalence of Alzheimer’s disease and other dementias are expected to rise significantly in the coming years.

“There’s an urgent need to address the crisis of Alzheimer’s disease and dementia in this country and globally,” she said. 

These new data confirm the high risk for dementia among minority groups as well as women who have often been underrepresented in research, said Carrillo.

The good news, though, is that this is “an exciting and hopeful time” in the field, with Alzheimer’s treatments being approved that slow the progression of early disease and with more treatments in the pipeline. 

“There are also better ways available now to detect and diagnose Alzheimer’s, and we’re learning more every day about risk reduction for Alzheimer’s and all other dementias,” Carrillo said.

Carrillo added the Alzheimer’s Association is leading the U.S. POINTER Study, a 2-year clinical trial evaluating whether lifestyle interventions targeting risk factors can protect cognitive function in older adults at increased risk for cognitive decline. Results of that study will be reported later this year at the Alzheimer’s Association International Conference.

She also pointed to last summer’s Lancet Commission Report showing that 40% of global dementia is potentially avoidable with behavioral and lifestyle changes.

“The main message is that there’s hope that we can, in fact, change the trajectory,” that by making such changes, “we won’t hit the numbers that this new paper talks about until 2060.”

However, she noted there’s still more work to be done. For example, she said, there’s an urgent need for more research into how to detect dementia as early as possible.

Carillo emphasized the importance of checking patients’ blood pressure and cholesterol, and conducting other tests to determine risk and discuss lifestyle changes that could result in dementia risk reduction. 

The study was supported by the National Institutes of Health (NIH) National Heart, Lung, and Blood Institute, National Institute of Diabetes and Digestive and Kidney Diseases, and National Institute on Aging (NIA); the National Institute of Neurological Disorders and Stroke Intramural Research Program; and the NIA Intramural Research Program. Coresh and Carillo report no relevant conflicts of interest.



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Publish date : 2025-01-13 16:05:16

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