This article requires a subscription to view the full text. If you have a subscription you may use the login form below to view the article. Access to this article can also be purchased.
Abstract
Objective: Patients with multiple sclerosis (MS) have more clinical exacerbations and T2 lesion activity during warmer weather. The current study is the first to investigate whether outdoor temperature is related to cognitive status across patients with MS (cross-sectional analysis), and whether cognitive status fluctuates with changes in outdoor temperature within patients with MS (longitudinal analysis).
Methods: For the cross-sectional analysis, 40 patients with MS and 40 healthy control (HC) subjects were recruited throughout the calendar year. Cognitive status (processing speed, memory) and outdoor temperature were recorded for the day of testing. We calculated partial correlations between cognitive status and temperature for patients with MS and HCs, controlling for demographic and disease variables. For the longitudinal analysis, cognitive status and outdoor temperature were recorded at baseline and 6-month follow-up in a separate sample of 45 patients with MS. We calculated the partial correlation between temperature and cognitive status at follow-up, controlling for baseline temperature and cognitive status (i.e., whether temperature changes are related to cognitive changes within patients with MS).
Results: Cross-sectionally, warmer temperature was related to worse cognitive status in patients with MS (rp = −0.45, p = 0.006), not in HCs (rp = 0.00, p = 0.984). Longitudinally, increased outdoor temperature from baseline to follow-up was related to a decline in cognitive status within patients with MS (rp = −0.39, p = 0.010).
Conclusions: Cognitive status in patients with MS is worse on warmer days, consistent with a previously established link between heat and lesion activity. Our findings have implications for clinical trial planning, treatment, and lifestyle decisions. We discuss cognitive status as a potential marker of quiescent exacerbations.
GLOSSARY
- CVLT-II=
- California Verbal Learning Test–Second Edition;
- HC=
- healthy control;
- MS=
- multiple sclerosis;
- SDMT=
- Symbol Digit Modalities Test;
- SRT=
- Selective Reminding Test;
- TVW=
- third ventricle width.
Footnotes
-
Study funding: Supported by grants from the National Multiple Sclerosis Society (RG3330A1/3 to N.C., MB0003 to J.D.) and the NIH (HD045798 to N.C., HD060765 to J.F.S.).
Editorial, page 938
- Received March 11, 2011.
- Accepted September 7, 2011.
- Copyright © 2012 by AAN Enterprises, Inc.
AAN Members: Sign in with your AAN member credentials (e-mail or 6-digit Member ID number)
Non-AAN Member subscribers: Sign in with subscriber credentials
Log in using your username and password
Purchase access
Disputes & Debates: Rapid online correspondence
NOTE: All authors' disclosures must be entered and current in our database before comments can be posted. Enter and update disclosures at http://submit.neurology.org. Exception: replies to comments concerning an article you originally authored do not require updated disclosures.
- Stay timely. Submit only on articles published within the last 8 weeks.
- Do not be redundant. Read any comments already posted on the article prior to submission.
- 200 words maximum.
- 5 references maximum. Reference 1 must be the article on which you are commenting.
- 5 authors maximum. Exception: replies can include all original authors of the article.
- Submitted comments are subject to editing and editor review prior to posting.