(Agencies)
Updated: 2007-12-06 08:10

CHICAGO -- Forgot where you put your keys? Or your car?

If you are over 60, it may just be a normal part of aging, US researchers said on Wednesday in a study that suggests brain structures deteriorate with age in otherwise healthy people.

An elderly man in a file photo. [Agencies]

The study, published in the journal Neuron, is part of an effort by researchers at Harvard University to understand the difference between normal, age-related declines and clinical impairment.

"We're trying to understand the edge of that boundary between normal aging and Alzheimer's disease," said Randy Buckner, a Harvard professor and Howard Hughes Medical Institute researcher who worked on the study.

Buckner and colleagues took brain scans of 55 adults ages 60 and over, and 38 younger adults ages 35 and younger. They used an imaging technique called PET to detect the presence of amyloid, a chemical typically associated with Alzheimer's disease, to rule out those whose memory declines were disease-related.

What they found is that some brain systems become less coordinated with age. "It looks like it is an effect of normal aging independent of Alzheimer's disease," Buckner said in a telephone interview.

They found brain structures called white matter tracks, which carry information between different regions of the brain, were deteriorating only in the older group.

"In young adults, the front of the brain was pretty well in sync with the back of the brain," Jessica Andrews-Hanna, a graduate student in Buckner's lab, said in a statement. "In older adults this was not the case. The regions became out of sync and they were less correlated with each other."

Buckner said the study suggests the cognitive decline in aging may be linked to communication problems between regions of the brain.

"We are talking about an effect that is progressing in the late decades of our lives," he said.

Not everyone was impaired to the same degree. This may help explain why some people who develop Alzheimer's disease succumb quickly and others decline more slowly.

"Some brains may be better prepared for the assault of Alzheimer's disease," Buckner said, adding that changes related to normal aging are mild compared with those associated with the progressive, degenerative disease that robs people of memory, reasoning and the ability to communicate.

"While it may mean our 80-year-old selves are not like when we were 20, it doesn't mean we are not doing extremely well compared to (the) disease," Buckner said.