A new study estimates that 2.4 million people, or 9.7% of Americans over age 71, have Alzheimer's disease, fewer than originally suspected. Unlike prior studies, which have focused on a small region or select cities, researchers assessed seniors in 42 states to arrive at the "best" estimates to date, reports Reuters. The data also shows the risk rises with age—nearly 30% of those over 90 have Alzheimer's.
A vice president for the Alzheimer's Association, which announced its estimate of 5 million-plus Americans with the disease in March, pooh-poohed the findings, saying Alzheimer's presents a serious crisis regardless of the figure. "Do I think any one of the studies has exactly the right number? The answer is no. None of them do." (Read more Alzheimers Association stories.)