February 5, 2025
The number of Americans with Alzheimer’s disease or other forms of dementia will double in the coming decades, with up to 1 million new cases a year by 2060, according to a new report. The findings underscore the urgent need for more effective ways to prevent or delay the onset of the mind-robbing illness, as a growing number of Americans are living longer.
For people who reach age 55, there is a 42 percent overall risk that they will develop dementia in their lifetime, the study found. The lifetime risk is higher in women, at 48 percent, largely because women tend to live longer than men. The risk in men in their mid-50s is 35 percent.
For those who remain dementia-free at age 75, the lifetime risk of developing dementia increases to over 50 percent. Advancing age is the largest risk factor for Alzheimer’s disease and other forms of dementia.
“Our study results forecast a dramatic rise in the burden from dementia in the United States over the coming decades, with one in two Americans expected to experience cognitive difficulties after age 55,” said study author Dr. Josef Coresh, founding director of the Optimal Aging at NYU Langone.
The increasing number of cases is directly tied to the aging of the U.S. population, the authors say. Beyond aging, a high risk of Alzheimer’s disease and other forms of dementia is linked to genetic factors, as well as high blood pressure and diabetes, obesity, unhealthy diets, lack of exercise, and poor mental health.
The predictions are based on an analysis of more than 15,000 adults who were part of the Atherosclerosis Risk in Communities Neurocognitive Study, which since 1987 has tracked the heart and vascular health of Americans living in four areas in Maryland, Minnesota, North Carolina and Mississippi. The study was more geographically, racially and socioeconomically diverse than other similar studies.
From 1987 until 2020, 3,252 of the study participants had been diagnosed with dementia. At age 75, dementia risk was about 4 percent; at 85, it was 20 percent; and by age 95, it was 42 percent. The risk was particularly high among Black adults, who also showed earlier onset compared to White adults.
The risk was also elevated in those who carry the APOE-E4 gene variant, a well-known risk factor for Alzheimer’s disease. The analysis found that people who had inherited two copies of APOE-E4, one from each parent, had a lifetime dementia risk of 59 percent, compared with lifetime risks of 48 percent for people with one copy and 39 percent for people without the variant. APOE-E4 carriers also developed dementia earlier than non-carriers, with differences observed by 70 years of age. The findings were published in the journal Nature Medicine.
The authors cited several steps that may help to reduce dementia risk, including working to improve heart and vascular health through medications and lifestyle changes such as regular exercise and a heart-healthy diet. Such measures can help keep blood pressure and cholesterol levels in a healthy range and also lower the risk of stroke, which can damage the brain and lead to dementia.
The authors also encouraged older people to get regular hearing checks and to wear hearing aids if needed, noting that only a third of Americans with hearing loss use hearing aids. Better hearing helps forestall Alzheimer’s disease and other forms of dementia by allowing people to remain more socially engaged and cognitively stimulated.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, Ph.D. Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Michael Fang, Jiaqi Hu, Jordan Weiss, et al: “Lifetime risk and projected burden of dementia.” Nature Medicine, January 13, 2025
