By 2060, 1 million U.S. adults are projected to develop dementia annually

By Priyanjana Pramanik, MSc.Reviewed by Danielle Ellis, B.Sc.Jan 13 2025

Approximately 42% of individuals may develop dementia after 55, with lifetime risks higher for Black individuals, women, and those with certain genetic markers

In an article in Nature Medicine, researchers calculated the risk of developing dementia between 55 and 95, projecting the yearly number of new dementia cases in the United States during 2020-2026 from a large and diverse cohort.

Background

The average of the U.S. population has increased significantly during the past 100 years, leading to an increase in later-life diseases like dementia, which now affects over 6 million Americans. Dementia is a major contributor to disability in older adults, resulting in at least 100,000 deaths annually and imposing an economic burden that exceeds $600 billion each year.

Lifetime dementia risk is a crucial public health metric that informs public awareness and policymaking. Understanding the lifetime risk of dementia is essential for raising awareness, improving prevention efforts, and guiding public health policies. Key health organizations use this measure to educate clinicians and patients. Estimates of lifetime risk also help refine dementia case projections, aiding in effective public health planning.

Previous studies in the United States estimated that between 11% and 14% of men, along with 19% to 23% of women, would develop dementia, but these figures may be underestimated due to older data and limited inclusion of diverse racial groups. Racial disparities in dementia risk remain underexplored, particularly among non-White populations.

About the study

Analyzing over three decades of health data, Josef Coresh and colleagues tracked 15,792 adults aged 45-64 from four U.S. communities from 1987 to 1989. Participants underwent clinical exams, cognitive tests, and interviews. From 2011, detailed neuropsychological testing and phone assessments were conducted.

The study excluded those with early dementia or missing data, resulting in 15,043 participants. Dementia was identified through in-person tests, phone interviews, and medical records. Data sources prioritized expert diagnoses from neuropsychological tests, phone-based cognitive scores, and hospital/death records.

Dementia onset was recorded from the earliest diagnosis. Analyses estimated lifetime dementia risk from age 55 to 95, considering death without dementia as a competing event. Secondary analyses used stricter definitions of dementia and different starting ages. The study also projected future dementia cases in the U.S. using age-specific incidence rates and census data covering the years 2020-2060 across various demographic groups.

Findings

The research team analyzed health data from 1987 to 2020 involving 15,043 Black and White participants over the age of 55 in the U.S. All participants were free of dementia at 55. After an average follow-up period of 23 years, they found that the risk of developing dementia by 95 was 42%. Dementia risk increased significantly after 75, with specific age-related risks: 0-4% from ages 55 to 75, 4-20% from 75 to 85, and 20-42% from 85 to 95.

The study showed variations in risk based on genetic factors, race, and sex. Women had a higher lifetime risk (48%) compared to men (35%), and Black adults had a slightly higher risk (44%) compared to White adults (41%). Those carrying two copies of the Apolipoprotein E epsilon 4 (APOE ε4) allele had the highest risk at 59%, compared to 48% for a single copy and 39% for none.

The data projected an increase in annual dementia cases from an estimated 514,000 in 2020 to 1 million by 2060, with the largest increases among those aged 75-95. The study highlighted early dementia onset and higher risk in Black individuals and those with APOE ε4 alleles.

Conclusions

This study concluded that over 40% of the participants developed dementia, with higher rates in women, Black adults, and APOE ε4 carriers. Compared to previous research, the estimated lifetime dementia risk was significantly higher, suggesting that prior studies may have underestimated dementia prevalence due to less comprehensive data collection methods.

Earlier studies, like the Framingham and Rotterdam studies, reported lower lifetime risks (23% and 14% for women and men, respectively). The higher risk found in this study may be due to the inclusion of more diverse populations and extensive dementia tracking through hospital records, cognitive testing, and phone interviews.

The findings underscore the need for targeted public health strategies focusing on prevention, particularly through cardiovascular health and hearing preservation. Given the projected doubling of annual dementia cases by 2060, public health policies should prioritize lifestyle interventions and address structural inequalities contributing to higher risks in minority populations.

Coresh and colleagues emphasize the urgent need for policies promoting healthy aging and reducing dementia risk through early intervention and broad-based health initiatives. The increasing burden of dementia calls for robust public health planning and resources to manage the anticipated rise in cases. More diverse population studies are also needed to understand dementia rates in other ethnic and racial groups.