Changes in White Matter May Predict Dementia Risk
07/21/09 Portland, OR
Research at Oregon Health & Science University supports the previously held notion that an increased rate of white matter degradation in the brain may help predict whether a person will develop dementia later in life. The results of the research are printed in the July 14 edition of the journal Neurology.
"Changes in brain white matter are frequently detected in MRI images as a person ages,” said Lisa Silbert, M.D., M.C.R., an assistant professor of neurology in the OHSU School of Medicine. “However, during our research, the kind of changes we witnessed in some subjects – relatively small changes in white matter in the brain over time – appears to correlate to the development of memory and thinking problems that might explain age-related cognitive changes that possibly lead to Alzheimer’s disease or other types of dementia.”
White matter is one of two major components in the brain - the other being grey matter. White matter is composed of myelinated axons, or nerve fibers, which act as a form of wiring in the brain that connects different processing areas (grey matter) of the brain to one another, much like electrical wiring in a home. White matter develops in the human brain through early adulthood but later degrades as a person ages.
To track white matter levels in the aging brain, scientists observed 49 people older than 65 for a approximately 10 years. During that time, each patient received at least three MRI brain scans to track whether there were any structural changes in the brain, including changes in white matter. Each participant also received annual cognitive tests to track their thinking skills over time. In tracking these patients, researchers observed that 24 of the 49 patients developed cognitive impairment.
The factor that predicts mental decline in some subjects but not in others appears to be the rate of change in white matter. In other words, those study participants who had the fastest rate of white matter degradation during the study were the most likely to suffer cognitive impairment.
“To put it simply, it’s not just how much damage you have, it’s how quickly you develop it,” added Silbert.
“Such findings are advancing our efforts to create rigorous imaging and biomarker standards that may allow us to characterize dementia in its earliest stages. Doing so will provide us the tools and tests needed to monitor progress of cognitive decline and responses to drug treatment,” said Marcelle Morrison-Bogorad, Ph.D., Division of Neuroscience director at the National Institute on Aging, the primary funder of this study.
The next steps for the research team are to determine what factors cause white matter to degrade and whether the process can be slowed. By slowing the progression of white matter degradation, researchers believe that it may be possible to delay the development of cognitive problems past the life expectancy of most people, resulting in increased cognitive health and quality of life for our elderly population.
The research was funded by the National Institute on Aging, a component of the National Institutes of Health; the Department of Veterans Affairs, a Paul B. Beeson Career Development Award in Aging, the Max Millis Fund for Neurological Research, and the Storms Family Fund at the Oregon Community Foundation.