CHICAGO – Keeping fit may help reduce brain atrophy in patients with early Alzheimer's, researchers said at the International Conference on Alzheimer's Disease.
An exercise-tolerance study confirmed that the hippocampus, one of the first brain regions to be affected in Alzheimer's, was significantly larger among patients who had higher fitness levels, Dr. Jeffrey Burns said at the meeting, which was sponsored by the Alzheimer's Association.
The association was also found with whole-brain volume during a previous study in the same cohort, Dr. Burns said in an interview. “Our data suggest that those in the lower half of fitness level have four times more brain atrophy than those in the higher-fitness group, compared to normal aging,” said Dr. Burns, director of the Hoglund Brain Imaging Center at the University of Kansas, Kansas City.
“Although we're a long way from proving that exercise decreases brain atrophy in Alzheimer's, this study certainly suggests that maintaining fitness has some kind of disease-specific effect.”
Dr. Burns and his colleague, Robyn Honea, Ph.D., evaluated cardiorespiratory fitness in 119 subjects older than 60 years; 56 had no dementia, while 63 had early-stage Alzheimer's.
All of the subjects undertook a treadmill test, which measured peak oxygen consumption during the most strenuous part of the test. All subjects also underwent magnetic resonance imaging to determine brain volume, Dr. Burns said in an interview.
All of the Alzheimer's patients showed disease-related atrophy in the hippocampus, temporal cortex, and parietal cortices. But those patients who had higher fitness levels had significantly greater white matter volume in the hippocampus, inferior temporal gyrus, and precentral gyrus.
“We found that the level of fitness was strongly related to volume in the parietal area, and also in the hippocampus,” Dr. Burns said. “That was most interesting because this is an area that's affected early in Alzheimer's, and the brain undergoes a lot of atrophy in that region as the disease progresses.”
Because the measurement tool–voxel-based morphometry–only provides a linear correlation, it was not possible to characterize the percentage of volume preserved in subjects who were more fit. “But on the whole, people who were more fit had larger brains, suggesting that maintaining fitness may slow the brain atrophy process in Alzheimer's,” Dr. Burns said.
Some animal studies suggest that exercise directly influences the disease process through a variety of pathways. “It may do something to the amyloid, but we also see lots of other changes in the body related to exercise. There are hormonal changes, changes in growth factors within the brain, and increased cerebral blood flow during exercise, which may increase brain vascularization.”
As understanding of the relationship grows, exercise prescriptions could become part of an Alzheimer's treatment program, Dr. Burns suggested.
“We want to be able to prescribe exercise and tell people how much is effective, but we're not there yet. The best advice we can give right now is what's good for the heart is good for the brain.”
The study presented at the meeting was the second study on this cohort, he added. In July, Dr. Burns and Dr. Honea published results showing that fitness positively influenced whole-brain volume in these same patients with early Alzheimer's (Neurology 2008;71:210-6).
Neither of the researchers disclosed any potential conflicts of interest.