Scientists have good news for older adults who occasionally forget why they walked into a room - and panic that they are getting Alzheimer's disease.

Not only is age-related memory loss a syndrome in its own right and completely unrelated to that dread disease, but unlike Alzheimer's it may be reversible or even preventable, researchers led by a Nobel laureate said in a study.

Using human brains that had been donated to science, as well as the brains of lab mice, the study for the first time pinpointed the molecular defects that cause cognitive aging.

In an unusual ray of hope, the study's authors conclude that drugs, foods or even behaviors might be identified that affect those molecular mechanisms, helping to restore memory.

Any such interventions would represent a significant advance to prevent memory decline, such as advice to keep cognitively active and healthy - which helps some people, but not all, and has only a flimsy scientific foundation. By identifying the "where did I park the car?" molecule, the discovery could also kick-start efforts to develop drugs to slow or roll back the memory lapses that accompany normal aging.

"This is a lovely set of studies," said Molly Wagster of the National Institute on Aging, an expert on normal age-related memory decline who was not involved in the new study. "They provide clues to the underlying mechanism of age-related memory decline and will, hopefully, move us down the road toward targeted therapeutics."

About 40 percent of Americans age 85 and older say they experience some memory loss, a 2009 survey by the Pew Research Center found, as did 27 percent of those 75 to 84 and 20 percent of those ages 65 to 74.

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