May 27, 2008
A large hippocampus -- a part of the brain devoted to memory -- may help ward off Alzheimer's disease, a new study reports. The findings offer new clues into why some elderly people remain mentally sharp and alert well into their 80s and beyond, even though their brains are riddled with the plaques and tangles of Alzheimer's disease.
The findings help support the notion of cognitive reserve, the theory that a brain rich in interconnections and working nerve cells may help to ward off the symptoms of Alzheimer's disease even when a certain amount of brain tissue is already damaged. With a larger hippocampus, the more brain cells. According to the theory, if some cells die off from the ravages of Alzheimer's or related ailments, enough cells remain so that people can continue to think and function normally.
From autopsies, researchers have long known that some people die with sharp minds and perfect memories, even though their brains are riddled with the plaques and tangles of Alzheimer's disease. The new research suggests that people who have a larger hippocampus, a seahorse-shaped part of the brain that is critical for memory, may as a result be protected against Alzheimer's.
"This larger hippocampus may protect these people from the effects of Alzheimer's disease-related brain changes," said study author Deniz Erten-Lyons, M.D., with Oregon Health & Science University in Portland. "Hopefully this will lead us eventually to prevention strategies."
For the study, presented April 15 at the American Academy of Neurology 60th Annual Meeting in Chicago, researchers evaluated the brains of 12 people who had sharp memories and thinking skills at the time of their death. Autopsies revealed that their brains contained large numbers of Alzheimer's plaques, even though they remained mentally sharp and alert. Their brains were compared to those of 23 people who had the same amount of plaques in their brains, but had been diagnosed with Alzheimer's disease before death.
Researchers found that the volume of the hippocampus area of the brain was 20 percent larger in the cognitively intact group compared to the Alzheimer's disease group with dementia. There were no other demographic, clinical or pathological differences between the groups. The results remained the same regardless of whether they were men or women, their age and the total brain volume.
The findings help to explain why many people remain mentally sharp well into their 80s and beyond, even though autopsies after death show that their brains contain extensive damage like that seen in Alzheimer's disease.
While nobody can control the size of their brains, experts advise that mentally stimulating activities like completing puzzles, traveling, learning a new language, playing a musical instrument, or doing crossword puzzles can help stimulate new connections between brain cells. These strengthened connections may help to preserve thinking and memory. Maintaining strong social ties and exercising into old age may also help to protect the brain, studies show.
To learn more about keeping the brain young, visit www.ALZinfo.org, The Alzheimer's Information Site.
Presented at the American Academy of Neurology 60th Anniversary Annual Meeting in Chicago, April 12 to 19, 2008.