Highly fit multiple sclerosis (MS) patients perform significantly better on tests of cognitive function than similar less-fit patients, a new study shows.
In addition, MRI scans of the patients showed that the fitter MS patients showed less damage in parts of the brain that show deterioration as a result of MS, as well as a greater volume of vital gray matter.
“We found that aerobic fitness has a protective effect on parts of the brain that are most affected by multiple sclerosis,” Ruchika Shaurya Prakash, lead author of the study and assistant professor of psychology at Ohio State University, said in a news release. “As a result, these fitter patients actually show better performance on tasks that measure processing speed.”
The study, conducted with colleagues Robert Motl and Arthur Kramer of the University of Illinois and Erin Snook of the University of Massachusetts, Amherst, appears online in the journal Brain Research.
The study involved 21 women diagnosed with relapsing-remitting MS. They were compared with 15 age- and education-matched healthy female controls. The study assessed fitness, cognitive function, and structural changes in all participants.
In order to measure fitness levels, the participants underwent a VO2 max test, in which they rode a stationary bicycle until they felt exhausted. During the test, they breathed into a mask which measured their oxygen consumption.
All the women also took a variety of tests designed to evaluate cognitive functions, such as processing speed and selective attention.
The third analysis involved MRIs of the participants, revealing any damage to their brains.
As expected, the MS patients did much worse than the healthy controls on the tests of brain functioning, and showed more deterioration in their brains as revealed through the MRIs.
Prakash notes significant differences between the more aerobically fit MS patients and those who were less fit.
“Physically fit MS patients had fewer lesions compared to those who weren’t as fit and the lesions they did have tended to be smaller,” Prakash said. “This is significant and can help explain why the higher-fit patients did better on tests of brain functioning.”
Aerobic fitness was also associated with less-damaged brain tissue in MS patients, both the gray matter and white matter.
The study found that fitness in MS patients was associated with larger volume of gray matter, accounting for about 20% of the volume in gray matter. That’s important, Prakash said, because gray matter is linked to brain processing skills.
“Even in gray matter that appeared relatively healthy, we found deterioration in the volume in MS patients,” she said. “But for some of the highest fit MS patients, we found that their gray matter volume was nearly equivalent to that of healthy controls.”
Another MRI analysis involved the integrity of the white matter in the brain. Higher-fit MS patients showed less deterioration of white matter compared to those who were less fit.
Overall, the three MRI tests in this study showed that parts of the brain involved in processing speed are all negatively affected by MS – but less so in patients who are aerobically fit.