Recent study reveals that old age may not be to blame for older people becoming forgetful.
It suggests that the same brain lesions that are associated with dementia are responsible for mild memory loss in old age.
"It appears these brain lesions have a much greater impact on memory function in old age than we previously thought," said study author Robert S. Wilson, PhD, with Rush University Medical Center in Chicago.
"Our results challenge the concept of normal memory aging and hint at the possibility that these lesions play a role in virtually all late-life memory loss," he said.
For the study, 350 Catholic nuns, priests and brothers were given memory tests annually for up to 13 years.
Tests included word list recall, naming, verbal, number and reading assessments. After death, the participant's brains were studied for lesions.
The study found that memory decline tended to be gradual until speeding up in the last four to five years of life.
Tangles, Lewy bodies, and stroke were all related to gradual memory decline. Almost no gradual decline was seen in the absence of tangles.
Both Lewy bodies and stroke approximately doubled the rate of gradual memory decline. Tangles and Lewy bodies were also related to rapid memory decline but explained only about one third of the effect.
"Understanding how and when these brain lesions affect memory as we age will likely be critical to efforts to develop treatments that delay memory loss in old age," said Wilson.
The National Institute on Aging supported the study.
The study was published in the September 15, 2010, online issue of Neurology, the medical journal of the American Academy of Neurology.