US Dementia Incidence Declines But Prevalence Continues to Rise Amid Population Aging

Recent research published in The BMJ indicates that new cases of dementia in the United States have been decreasing since 2015, while the number of individuals living with the condition continues to grow. In 2021, nearly 2.9 million Medicare beneficiaries, accounting for about 12%, had a dementia diagnosis. The study analyzed medical claims data from over 5 million Medicare fee-for-service beneficiaries aged 66 and older between 2015 and 2021, revealing that after adjusting for age and sex differences, the incidence of dementia dropped from 3.5% to 2.8%. Conversely, the prevalence increased from 10.5% to 11.8% during the same period.

The study also found disparities in dementia burden across different populations. Men exhibited a slightly higher incidence than women in 2015 (3.5% vs. 3.4%), but by 2021, the rates slightly declined to 2.9% for men and 2.6% for women. Despite this, women remained the majority of individuals with dementia, representing about 60% of cases in 2021, largely due to their longer lifespans.

Furthermore, the research highlighted significant racial and socioeconomic disparities. Black beneficiaries experienced the highest incidence and prevalence rates, with 4.2% in 2015 and 3.1% in 2021, surpassing white and Hispanic populations. Those living in socioeconomically deprived neighborhoods also faced a greater burden of dementia.

The decline in new dementia diagnoses may be linked to improved management of cardiovascular risk factors and the impact of COVID-19, which could have led to underdiagnosis. The rise in prevalence, however, suggests more people are surviving longer after diagnosis or living longer with the disease.

The authors emphasize the importance of health equity, calling for policies that address disparities based on race, sex, and socioeconomic status. They stress the need for further research to understand underlying mechanisms and to develop targeted strategies for prevention and care. These findings provide a valuable snapshot of clinical practice trends and highlight the ongoing challenge of managing dementia amid demographic shifts.

Source: https://medicalxpress.com/news/2025-05-dementia-cases-decline-people-condition.html