WASHINGTON As much as 5 percent of the population past the age of 70 could develop a type of memory loss known as mild cognitive impairment every year -- far more than previous estimates, U.S. researchers reported on Monday.
The numbers rise to 7 percent for those older than 80, the team at the Mayo Clinic in Rochester, Minnesota, found.
"If we extrapolate these findings to the baby boomers, who are aging into the period of risk, we're talking about a significant number of individuals who may become cognitively impaired in the very near future," Dr. Ronald Petersen, the neurologist who led the study, said in a statement.
"Consequently, if we don't find a cure or treatment to delay the onset of Alzheimer's disease, we're going to be overwhelmed by the burden of these individuals on the health care system."
Peterson's team was studying 2,000 people past the age of 70 who started out normal and healthy. Every year, more than 5 percent had enough loss of mental function and memory to be diagnosed with mild cognitive impairment, known as MCI.
"The rates that we had found are considerably higher than we had anticipated," Peterson said.
MCI is defined as having memory problems -- more severe than occasionally or even regularly losing car keys -- slower thinking and a reduced ability to learn. Memory problems might include missing regular appointments or activities.
MCI is a first step toward Alzheimer's, an incurable disease that has few treatments and the leading cause of dementia, Peterson told the Alzheimer's Association International Conference on Alzheimer's Disease in Chicago.