A new study shows that 42% of Americans ages 55 and older are at risk of developing dementia at some point in their lives. This risk is more than double that found in earlier studies.

Dementia, a condition that causes a decline in memory, focus and decision making, is expected to see 5,00,000 new cases this year, with the number rising to one million annually by 2060. The increase in cases is mainly due to: The aging population in the US.

Besides age, other factors associated with higher dementia risk include genetics, high blood pressure, diabetes, obesity, poor diet, lack of physical activity, and mental health problems.

Researchers attribute previous underestimation of dementia cases to limited tracking of early-stage dementia, underreporting in minority groups, and unreliable documentation in medical records.

The study, funded by the National Institutes of Health, was led by NYU Langone Health with contributions from Johns Hopkins University and other institutions.

The data come from the long-running ARIC-NCS study, which has tracked the heart and brain health of nearly 16,000 participants since 1987.

The findings, published in Nature Medicine, showed that 3,252 participants developed dementia between 1987 and 2020. This translates to a 42% lifetime risk for middle-aged Americans, with men facing a 35% risk and women facing a 48% risk. The greater risk for women is partly because they live longer.

Black adults and people with the APOE4 gene variant, a major genetic risk factor for Alzheimer’s, were at even higher risk (45–60%).

Dr. Joseph Koresh, a senior researcher and epidemiologist at NYU Langone, warns that the incidence of dementia is set to increase rapidly, affecting nearly half of Americans over 55 in the coming decades. They noted that women’s longevity and the increasing number of older adults contribute to this trend.

The study also highlights that the lifetime risk of dementia increases by over 50% in people who live to be 75. However, policies aimed at preventing heart disease, such as managing blood pressure and diabetes, may help reduce the incidence of dementia.

Dr. Koresh has called for greater efforts to address hearing loss, which is linked to dementia, by making hearing aids more affordable and accessible.

He said there is a need to address racial health disparities, particularly in black communities, by improving education and nutrition, which can protect against cognitive decline later in life.

As the incidence of dementia increases, health policymakers face significant challenges, requiring better prevention strategies and expanded care services.