• In a recent retrospective study, researchers analyzed the connection between high ambient temperatures and clinic visits among U.S. veterans with multiple sclerosis (MS).
• The authors reviewed information from 27,290 people who made 530,075 total hospital and clinic visits during the three-year study period.
• Researchers concluded that sudden temperature and humidity increases caused the risk of MS clinic visits to rise.

A new study has found that sudden increases in ambient temperature and humidity levels could boost the risk of hospital visits for people with multiple sclerosis. The study results could help people with MS better understand the connection between high ambient temperatures and their symptoms.

The report, published on June 2 in the International Journal of Environmental Research and Public Health, focused on the volume of clinic and hospital visits among people with MS, based on the ambient temperature in their region at the time. The retrospective analysis examined data from U.S. veterans with MS who were treated at Veteran Affairs hospitals or clinics from 2010 to 2013.

The study authors reviewed information from 27,290 people who made 530,075 total visits during the analysis period. They then cross-referenced that information against meteorological data from the National Climatic Data Center to track the weather conditions in the regions where the veterans were seen and assess the impact of the weather on MS-related visits. Researchers found that “clinic visits were 9 percent more likely to occur in the spring, summer, and fall months (March – October) than in the winter.” Specific data varied based on the climate in different geographic regions, “suggesting variations in adaptation to region-specific climatic conditions,” the study’s authors wrote.

Neurologists have long observed that increases in body temperature — such as those caused by exercise — can slow nerve conduction and temporarily worsen MS symptoms, a phenomenon called Uhthoff’s sign. The study’s researchers concluded that sudden increases in ambient temperature and humidity levels also could affect MS symptoms, increasing the risk of MS clinic visits.

The study authors added that these findings might help health care providers and people with MS develop region-specific strategies to deal with temperature shifts and their impact on MS symptoms.