Older Americans are having less trouble with their memories, and it may be because they spent more time in school, researchers said Wednesday.
They found the rate of cognitive impairment -- which includes a range of ills from significant memory loss to Alzheimer's disease -- fell 3.5 percentage points among people 70 and older between 1993 and 2002.
"We found a clear relationship. The more education people had, the better they performed on cognitive tests," said Dr. Ken M. Langa of the University of Michigan.
Langa's study appears in the journal Alzheimer's & Dementia.
Langa said the research reinforced other studies that suggested people who do mentally challenging tasks early on build up a reserve of brain power that helped them withstand later injuries to the brain, such as a mini-stroke.