The study, presented at the 98th scientific assembly and annual meeting of the Radiological Society of North America (RSNA) in Chicago, is the work of Konstantinos Arfanakis and colleagues, from Rush University Medical Center and Illinois Institute of Technology.
"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," says Arfanakis, an associate professor in the Department of Diagnostic Radiology and Nuclear Medicine at Rush University Medical Center, in a press statement.
White MatterPrevious studies have suggested keeping mentally active in old age also appears to keep the mind sharp, but few have looked at the effect on physical brain health, such as the structural integrity of white matter.
White matter comprises the axons or nerve fibers, the "electrical wiring" that transmits information around the brain.
Diffusion AnisotropyFor their study, Arfanakis and colleagues used a type of MRI scan called DTI, short for diffusion tensor imaging, which measures diffusion anisotropy, or how well water molecules travel in different directions in the brain. ("Anisotropy" literally means having different properties in different directions).
In white matter, water molecules move more easily in directions that are parallel to the "electrical wires" or axons, and less easily in directions that are perpendicular to them, because their path is impeded by axon or nerve fiber structures, such as their membranes and myelin protective sheath.
DTI takes a measure of this difference in water travelling or diffusion rates: the bigger the difference, the more diffusion there is in one direction compared to the other, explains Arfanakis.
Thus healthy brains have bigger diffusion anisotropy values than brains where the structures have deteriorated, such as through aging, injury or disease.
"Lower diffusion anisotropy values are consistent with aging," says Arfanakis.
The StudyThe study involved 152 people of average age 81 years who were taking part in the Rush Memory and Aging Project, a large study examining risk factors for Alzheimer's disease.
Detailed clinical evaluations had established that none of the participants had dementia or mild cognitive impairment.
The researchers invited the participants to indicate how often in the past year they had engaged in mental activities such as reading newspapers and magazines, writing letters, and playing board games and cards. They had to indicate the frequency on a scale of 1 to 5.
During the 12 months following their clinical evaluation, the participants also underwent MRI brain scans that allowed the researchers to produce diffusion anisotropy maps.
The ResultsThe results showed a significant link between the frequency of mental activity and diffusion anisotropy values: more mental activity was linked to higher values.
"Keeping the brain occupied late in life has positive outcomes," says Arfanakis, after explaining what they found:
"Several areas throughout the brain, including regions quite important to cognition, showed higher microstructural integrity with more frequent cognitive activity in late life."
Arfanakis says diffusion anisotropy values start falling at around age 30.
"Higher diffusion anisotropy in elderly patients who engage in frequent cognitive activity suggests that these people have brain properties similar to those of younger individuals," he adds.
Next StepHe and his team are still following the participants, so they can see what happens to their diffusion anisotropy over time.
Strictly speaking, the current study only establishes there is a link between white matter integrity and mental activity, it does not prove that one causes the other, but by following the participants over time, Arfanakis and colleagues hope to demonstrate the link is causal.
Written by Catharine Paddock PhD