An estimated 5.1 million Americans have Alzheimer’s disease, according to an annual study by the Alzheimer’s Association, Chicago.

Of these, 4.9 million are age 65 and older. Another 200,000 are younger than 65.

AA projects that there will be 454,000 new cases of Alzheimer’s by 2010, up from an estimated 411,000 in 2000. That figure could rise to 615,000 by 2030 and to 959,000 by 2050.

A projected 7.7 million people age 65 and over will have Alzheimer’s by 2030, an increase of more than 50% over the current number, according to the report.

The disease develops in someone in the U.S. every 72 seconds, and by 2050 someone will develop the disease every 33 seconds, the report projects.

“The number of Americans surviving into their 80s and 90s is expected to grow because of national demographics as well as advances in medicine, medical technology and other social and environmental improvements,” the report states. “Since the incidence and prevalence of Alzheimer’s disease increase with advancing age, the number of persons with the disease is expected to grow as a proportion of this larger older population.”