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Multiple sclerosis study documents negative effect of warmer weather on cognition

March 13, 2012
Kessler Foundation
Scientists have shown that outdoor temperature significantly impacts cognitive functioning in multiple sclerosis (MS). In cross-sectional and longitudinal samples, patients performed worse on processing speed and memory tasks during warmer outdoor temperatures. Previous research documented increased disease activity during warmer months; this study is the first to show that cognition also fluctuates. This is the first study to support the subjective impression of patients with MS that warm weather negatively affects their cognition.

Kessler Foundation scientists have shown for the first time that outdoor temperature significantly affects cognitive functioning in multiple sclerosis (MS). While it is recognized that disease activity increases during warmer months, this is the first study to document that cognition also fluctuates. During warmer outdoor temperatures patients with MS performed worse on tasks involving processing speed and memory. An estimated 50 to 65% of people with MS experience problems with thinking, learning and remembering that can be disabling.

According to the results, cognitive performance may be a more sensitive indicator of subclinical disease activity than traditional assessments.

In the study, which spanned the calendar year, 40 individuals with MS and 40 people without MS underwent cognitive assessment of memory and processing speed. People with MS scored 70 percent higher on cooler days; no association was found for individuals without MS. Funding was provided by the National MS Society and the NIH.

According to Victoria M. Leavitt, Ph.D., research scientist, and the study's principal investigator, these findings have implications for patients, clinicians and researchers. "This information is relevant to making life decisions and choosing therapies and evaluating their effects," said Dr. Leavitt. "Outdoor temperatures may be an important consideration when designing and conducting clinical trials, many of which span six months." For example, taking baseline measurements during warmer months could inflate positive findings. The study's co-investigators are James F. Sumowski, Ph.D., Research Scientist, Nancy Chiaravalloti, Ph.D., Director of Neuropsychology & Neuroscience Research, and John DeLuca, Ph.D., VP for Research.

Kessler Foundation is nationally and internationally known for cognitive rehabilitation research in MS and traumatic brain injury. Its neuroscience research supports the theory of cognitive reserve, ie, people with MS who lead intellectually enriching lives are less likely to experience cognitive decline. A recent publication documented changes in brain activity on fMRI associated with effective memory retraining in people with MS.

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Materials provided by Kessler Foundation. Note: Content may be edited for style and length.

Journal Reference:

  1. V. M. Leavitt, J. F. Sumowski, N. Chiaravalloti, J. DeLuca. Warmer outdoor temperature is associated with worse cognitive status in multiple sclerosis. Neurology, 2012; DOI: 10.1212/WNL.0b013e31824d5834

Cite This Page:

Kessler Foundation. "Multiple sclerosis study documents negative effect of warmer weather on cognition." ScienceDaily. ScienceDaily, 13 March 2012. <>.
Kessler Foundation. (2012, March 13). Multiple sclerosis study documents negative effect of warmer weather on cognition. ScienceDaily. Retrieved July 16, 2024 from
Kessler Foundation. "Multiple sclerosis study documents negative effect of warmer weather on cognition." ScienceDaily. (accessed July 16, 2024).

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