On Jan. 13, 2025, a study led by NYU Langone Health shows that the risk of developing dementia at any time after age 55 among Americans is 42 percent, more than double the risk reported by older studies.

That dementia risk translates into an estimated half-million cases this year, rising to a million new cases a year by 2060, according to the new work. Dementia involves progressive declines in memory, concentration, and judgment. The increasing number of cases is directly tied to the aging of the U.S. population. Beyond aging, a high risk of dementia is linked to genetic factors, as well as high rates of hypertension and diabetes, obesity, unhealthy diets, lack of exercise, and poor mental health.

The study authors attribute the previous underestimates of dementia risk to unreliable documentation of the illness in health records and on death certificates, minimal surveillance of early-stage cases of dementia, and the under reporting of cases among racial minority groups, which are disproportionately vulnerable.

The study concludes that from 1987 until 2020, there were 3,252 study participants who were documented as having developed dementia. This translates to an overall lifetime risk for dementia among middle-aged Americans of 42 percent, which is an average of the 35 percent risk in men and the 48 percent risk in women. The excess risk in women was largely due to their lower death rates. The study was published in the journal Nature Medicine online.