March 24, 2010
Science Daily/American Chemical Society
A study of the brains of people who stayed mentally sharp into their 80s and beyond challenges the notion that brain changes linked to mental decline and Alzheimer's disease are a normal, inevitable part of aging.
In a presentation given at the 239th National Meeting of the American Chemical Society (ACS) in San Fransisco March 23, Changiz Geula, Ph.D. and colleagues described their discovery of elderly people with super-sharp memory -- so-called "super-aged" individuals -- who somehow escaped formation of brain "tangles."
The tangles consist of an abnormal form of a protein called "tau" that damages and eventually kills nerve cells. Named for their snarled, knotted appearance under a microscope, tangles increase with advancing age and peak in people with Alzheimer's disease.
"This discovery is very exciting," said Geula, principal investigator of the Northwestern University Super Aging Project and a professor of neuroscience at the Cognitive Neurology and Alzheimer's Disease Center. "It is the first study of its kind and its implications are vast.
We always assumed that the accumulation of tangles is a progressive phenomenon throughout the normal aging process. Healthy people develop moderate numbers of tangles, with the most severe cases linked to Alzheimer's disease. But now we have evidence that some individuals are immune to tangle formation.
The evidence also supports the notion that the presence of tangles may influence cognitive performance. Individuals with the fewest tangles perform at superior levels. Those with more appear to be normal for their age."’
The scientists found that super-aged people appear to fall into two subgroups: Those who are almost immune to tangle formation and those that have few tangles.
"One group of super-aged seems to dodge tangle formation," Geula explained. "Their brains are virtually clean, which doesn't happen in normal-aged individuals. The other group seems to get tangles but it's less than or equal to the amount in the normal elderly. But for some reason, they seem to be protected against its effects."