THURSDAY, Feb. 17 (HealthDay News) -- People with multiple
sclerosis may have more problems remembering, learning and
processing information in warm weather than in cooler months, a
small study suggests.
Researchers at the Kessler Foundation in West Orange, N.J.,
found that patients with MS performed 70 percent better on tests
involving thinking, or cognitive functioning, on cooler days than
they did at warmer times of the year.
"These findings are important because in many cases, cognitive changes take a greater psychological toll on MS patients than changes in motor symptoms do," said the study's lead author, Victoria Leavitt, a neuropsychologist and post-doctoral fellow at the Kessler Foundation Research Center.
"People who have MS often leave the workforce before their motor symptoms emerge, and the reason they'll often give is fatigue," said Leavitt. "But it's possible that it may be related to these changes in cognition, which are requiring them to use their brains in a different way."
The findings, released Feb. 17, are scheduled to be presented in
April at the American Academy of Neurology annual meeting in
For the study, 40 people with MS and 40 without the nervous
system disease took the same cognitive tests at different times
throughout the calendar year. The researchers recorded the
temperature on each day that the patients were tested. While the MS
patients performed better on these tests on cooler days, there was
no difference in the test results of the healthy controls.
The reason why temperature changes might affect MS patients'
thinking isn't known, but Leavitt said one possible explanation is
that the underlying mechanisms that regulate the body's reaction to
heat may work less effectively in people with MS.
Leavitt said her work was a direct result of a 2010 study by
scientists at Brigham and Women's Hospital in Boston, which showed
that brain lesion activity in MS patients was two to three times
higher during the months of March through August, compared with
other times of the year. That paper was published last August in
Another MS researcher called Leavitt's study "an important
follow-up" to the paper by Brigham and Women's researchers.
"It's a fairly recognized phenomenon that MS patients complain of increased symptoms in the summer months, but this is the first time that someone has really looked at cognitive functioning related to temperature," said Dr. Jonathan L. Carter, associate professor of neurology at the Mayo Clinic College of Medicine in Scottsdale, Ariz.
The next steps, said Carter, "may be to find out if these
changes are related to new disease activity or just worsening
deficits related to the existing lesions, and also look at whether
existing drug therapies might help with this temperature-related
"One really important bottom-line implication of our findings is for researchers who are performing drug trials," Leavitt added. "They need to consider this temperature effect when they're doing baseline cognitive testing. The results could be very different if you take your baseline in June versus December," she said.
Depending on the results of future research, it's also
conceivable that the findings could influence life decisions made
by people with MS, the researchers say.
Experts note that research presented at meetings has not been
subjected to the same type of rigorous scrutiny given to research
published in peer-reviewed medical journals.
For more about multiple sclerosis, visit the
American Academy of Family Physicians.