“Patients did worse on cognition tests in warm weather…”
… Now scientists studying multiple sclerosis (MS) have found that environmental changes affect how well patients respond in cognition tests, indicating that temperature plays a role in how this neurological illness progresses.
Multiple sclerosis is a degenerative disease in which the body’s own cells attack the insulation around nerve cells, making it difficult for nerves to transmit signals. This leads to lesions in the brain’s white matter and in some cases impairs movement, vision, hearing and speech. For patients, the disease can gradually get worse over time, or it can progress in bouts of symptoms.
According to the World Health Organization, MS is the most common neurological disorder among young adults. In a 2008 report, the group noted that for MS, “symptoms appear at around 30 years of age, when people are most economically active and when they would be most likely to be starting or supporting a family.”
Researchers are still trying to figure out what causes the disease, but Victoria Leavitt, a research scientist at the Kessler Foundation Research Center, has observed that higher temperatures affect how MS patients think, remember and react. The journal Neurology published her findings online earlier this month.
Leavitt said she started to notice anecdotal reports from MS patients who said they felt fatigued during the summer. Other research showed increased MS-related brain lesions when there were warm outdoor temperatures. She wondered whether the two were related and if patients were really experiencing fatigue or if their thinking was impaired.
MS is more likely to affect cognition — how people perceive, think and react — because more brain areas are involved in these processes, while movement and senses tend to be localized to specific regions. “It’s a more sensitive measure of brain activity,” said Leavitt.
But these symptoms often take a back seat to other problems like trouble talking, seeing and walking. “If you can’t get out of bed in the morning, it seems to be a bigger problem than feeling a little fuzzy,” said Leavitt. Cognition is also harder to monitor than tremors, blurred vision and a wobbly gait.
As a result, many doctors define and observe MS in terms of its more visible symptoms, making it difficult to track how the disease behaves under different circumstances and overlooking what Leavitt described as “quiescent disease activity,” where the illness progresses without outward signs. “Not seeing it doesn’t mean it’s not there,” she said.
To see how temperature affects MS patients and their cognition, Leavitt and her team administered standardized tests. These examinations are similar to IQ tests while also assessing memory and speed. The researchers administered the tests over a calendar year to 40 MS patients along with people without the disease in New Jersey…
The team also studied 45 different MS patients over a six-month interval and found these patients did worse on cognition tests in warm weather, controlling for differences in how their respective illnesses progressed. On the other hand, healthy patients showed no performance changes between cool and warm weather. Since subjects took the tests in an air-conditioned environment, the outdoor temperature effect is likely to be cumulative as patients are exposed to warmer weather over time, according to Sumowski….