Dementia epidemic coming among people over age 90

The oldest old are the fastest growing segment of the US population, and dementia rates among them "threatens to become an epidemic with enormous public health impact," says a neurology scientist at the University of California, Irvine.

The World Health Organization has said dementia affects up to 10 percent of the North American population age 65 and older, and that Alzheimer's disease accounts for two-thirds of those cases.

Maria Corrada-Bravo writes in the Archives of Neurology that dementia incidence increases exponentially beyond age 90. The increase is almost 13 percent per year in the 90- to 94-year-old age group, 21 percent per year in the 95- to 99-year-old age group, and almost 41 percent per year in those over age 100.

"Our findings show dementia incidence rates almost double every five years in those 90 and older," Corrada-Bravo says.

Previous work has estimated America has 2 million people ages 90 and older. That number is expected to reach 8.7 million by 2050, making the oldest-old the fastest growing segment of the U.S. population.

The study appears in the February issue of Annals of Neurology. You can also read a report about the study in Science Daily.