Konstantinos Arfanakis, Ph.D., and colleagues from Rush University Medical Center and Illinois Institute of Technology in Chicago studied what effect late-life cognitive activity might have on the brain’s white matter, which is composed of nerve fibers, or axons, that transmit information throughout the brain.
“Reading the newspaper, writing letters, visiting a library, attending a play or playing games, such as chess or checkers, are all simple activities that can contribute to a healthier brain,” Dr. Arfanakis said.
The researchers used a magnetic resonance imaging (MRI) method known as diffusion tensor imaging (DTI) to generate data on diffusion anisotropy, a measure of how water molecules move through the brain. In white matter, diffusion anisotropy exploits the fact that water moves more easily in a direction parallel to the brain’s axons, and less easily perpendicular to the axons, because it is impeded by structures such as axonal membranes and myelin.
“This difference in the diffusion rates along different directions increases diffusion anisotropy values,” Dr. Arfanakis said. “Diffusion anisotropy is higher when more diffusion is happening in one direction compared to others.” The anisotropy values in white matter drop, however, with aging, injury and disease.
“In healthy white matter tissue, water can’t move as much in directions perpendicular to the nerve fibers,” Dr. Arfanakis said. “But if, for example, you have lower neuronal density or less myelin, then the water has more freedom to move perpendicular to the fibers, so you would have reduced diffusion anisotropy. Lower diffusion anisotropy values are consistent with aging.”
The study included 152 elderly participants, mean age 81 years, from the Rush Memory and Aging Project, a large-scale study looking at risk factors for Alzheimer’s disease. Participants were without dementia or mild cognitive impairment, based on a detailed clinical evaluation. Researchers asked the participants to rate on a scale of 1 to 5 the frequency with which they participated in a list of mentally engaging activities during the last year. Among the activities were reading newspapers and magazines, writing letters and playing cards and board games.