Restless legs syndrome in MS linked to cognitive impairment

SEATTLE – A new study finds that patients with both multiple sclerosis (MS) and restless legs syndrome (RLS) were more likely to suffer from self-perceived cognitive impairment. The results suggest that sleep dysfunction exacerbated by RLS could affect cognition in patients with MS, study lead author Katie L. Cederberg, CPT, a doctoral student in the department of physical therapy at the University of Alabama at Birmingham, said in an interview. She spoke at the annual meeting of the Consortium of Multiple Sclerosis Centers, where she presented the findings.

“RLS severity did predict cognitive impairment,” she said. However, she added, “this is just a snapshot, and we need to do more research.”

Sleep problems, including RLS, are more common in patients with MS than in the general population. “Current research suggests that anywhere from 19% to 67% of individuals with MS experience some sort of sleep difficulty, with rates as high as 80% in some samples,” a 2015 report noted.

As for RLS, a 2018 systematic review and meta-analysis found that “pooled RLS prevalence among MS patients of various ethnicities was 26%, and prevalence was lower in Asia (20%) than outside Asia (27%). Prevalence was higher among cross-sectional studies (30%) than among case-control studies (23%). RLS prevalence was higher among female than among male MS patients (26% vs. 17%), and it was higher among MS patients than among healthy controls (odds ratio, 3.96, 95% confidence interval, 3.29-4.77, P less than .001) (Sleep Med. 2018 Oct;50:97-104).

Ms. Cederberg said the frequency of RLS in patients with MS spurred her and colleagues to explore whether it may affect cognitive function.

For their study, the researchers surveyed 275 patients with MS (mean age = 60, 81% female, 33% employed, 95% white, 66% with relapsing-remitting MS). Of the 275, 75 appeared to have RLS. These patients were similar to the non-RLS patients in multiple areas, but they diverged in scores on the brief Multiple Sclerosis Neuropsychological Questionnaire, which measures self-perception of cognition.

Those with both MS and RLS scored 21.9 (± 11.7) on the test, while those with MS scored 18.0 (± 11.0), P = 0.023.

Analyses linked greater RLS severity to worse self-perceived cognitive impairment and sleep quality. “The diagnosis and treatment of RLS symptoms and other effectors of sleep quality could improve cognitive consequences of MS,” the authors concluded.

The National MS Society funded the study. The study authors reported no relevant disclosures.