Image of male nurse pushing senior woman in a wheelchair in nursing facility

Nearly 15% of seniors age 71 and older have dementia of some sort – and nearly two-thirds of those have Alzheimer’s disease, a new analysis suggests.

That is equal to about 3.4 million Americans with dementia of some kind, according to the National Institutes of Health-sponsored study. It is the first to estimate rates of dementia and Alzheimer’s disease using a nationally representative sample of seniors across the country, researchers said.

The analysis was part of the Aging, Demographics and Memory Study (ADAMS), which itself is a part of the larger Health and Retirement Study (HRS). Findings were published online this week in “Neuroepidemiology.”