Some people experience slower brain aging. Are you one of the lucky ones?
Now they have a preliminary answer. Scientists examined the brains of five deceased people considered super aged because of their high performance on memory tests when they were more than 80 years old and compared them to the brains of elderly, non-demented individuals. Researchers found the super aged brains had many fewer fiber-like tangles than the brains of those who had aged normally. The tangles consist of a protein called tau that accumulates inside brain cells and is thought to eventually kill the cells. Tangles are found in moderate numbers in the brains of elderly and increase substantially in the brains of Alzheimer's disease patients.
These results suggest that treatments for Alzheimer's disease that aim to prevent tangle formation will provide benefit to all people as their brains age. That's good news. A lot of effort is going into Alzheimer's treatment and the treatment development efforts aimed at tangles strike me as having a good chance of succeeding.
"This new finding in super aged brains is very exciting," said Changiz Geula, principal investigator of the study and a research professor of neurology at the Cognitive Neurology and Alzheimer's Disease Center at Northwestern's Feinberg School. "It was always assumed that the accumulation of these tangles is a progressive phenomenon through the aging process. But we are seeing that some individuals are immune to tangle formation and that the presence of these tangles seems to influence cognitive performance." Individuals who have few tangles perform at superior levels, while those who have more tangles appear to be normal for their age, Geula noted.
This begs the question: why are some people immune to tangle formation? Do they have immune systems that attack the tangles? Or do they have some genetic variant that lowers oxidative stress in the brain?
Geula will present his findings Sunday, November 16, at the Society for Neuroscience annual meeting in Washington, D.C.
The number of plaques in the brains of the super aged was similar to that in the brains of the normally aging group. The plaque is an aggregation of protein called amyloid that becomes deposited outside the brain cell and disrupts communication between neurons. Like tangles, plaques also are found in modest numbers in the brains of aged individuals and show a dramatic increase in number in Alzheimer's disease.
Geula said the lower number of tangles in the super aged appears to be the critical difference in maintaining memory skills.
Some of the super aged in the study performed memory tasks at the level of people who were about 50 years old. For example, after being told a story, they were able to remember it immediately after and still accurately recall its details 30 minutes later. They also remembered a list of 15 words and recalled these words equally well when tested after 30 minutes.
Stopping brain aging at age 50 wouldn't be ideal. But I'd take it as a good starter. Prevention of tangles won't stop all brain aging though. For example, demyelination (loss of insulation on neurons) would still proceed. We probably need some sort of cell therapy to reverse that process.
|Share |||Randall Parker, 2008 November 18 08:03 AM Brain Aging|