Brains Do Not Shrink Faster As Healthy People Get Older

"Conventional wisdom has it that the loss of brain tissue accelerates as people get older. We found that even though healthy people do lose brain tissue as they age, the rate of the brain's shrinking can stay relatively constant, and relatively small, well into the 90's and beyond," said Jeff Kaye, M.D., professor of neurology and director of the Aging and Alzheimer Center at Oregon Health Sciences University and the Portland Veterans Affairs Medical Center.

Kaye's research team analyzed the volume of several regions of the brain of 46 patients ages 65 to 95. To be included in the study, patients needed to be healthy and show no signs of Alzheimer's disease or other dementia. The patients were divided into three age groups: the "young-old" (65 to 74 years old), the "middle-old" (75 to 84 years old) and the "oldest-old" (85 to 95 years old). While the study found the volume of certain brain regions diminished over time, the loss of tissue among the study patients was one percent or less per year. The changes in brain volume were measured with magnetic resonance imaging (MRI) scans.

Previous research which followed elderly patients over a long period of time has suggested that the brain does shrink faster the older one gets. "But those earlier studies probably included people destined to develop Alzheimer's disease, even though the disease had not yet been diagnosed.Those study subjects would have lost brain tissue at a faster rate than healthy older people, thus throwing off the study results," said Kaye. By breaking the OHSU and VA study patients into three groups, the researchers could easily screen out those who showed signs of Alzheimer's disease or other dementia, and get a clearer picture of the rate of brain tissue loss within each healthy group.

"This research suggests that it's possible to age normally through one's whole lifespan, though the risk of dementia is always there," said Kaye. Kaye says the study results may be a tool for identifying those at risk of dementia. "For example, if people have an accelerated rate of tissue loss in the brain, that may tell us they are going to develop dementia,"

And the results offer encouragement for looking for treatments that prevent dementia. "Rapid brain tissue loss and the dementia that often goes with it don't appear to be an automatic consequence of aging. So if we can delay the onset of Alzheimer's disease by only a few years, we could allow patients to finish out their lives normally," said Kaye.

This study is part of a larger study on brain aging and cognition supported by the federal Department of Veterans Affairs, the National Institute on Aging and the Alzheimer Research Alliance of Oregon.