Restless Legs Syndrome Severity and Cognitive Function in Adults With Multiple Sclerosis: An Exploratory Pilot Study

Abstract

Background: Restless legs syndrome (RLS) is a sleep disorder present in as many as 26% of persons with multiple sclerosis (MS) and can be associated with cognitive function. The present study examined the relationships between RLS symptoms (severity, frequency, occurrence) and cognitive function in adults with MS who have RLS.

Methods: Twenty-two participants attended 1 laboratory session and completed the International Restless Legs Syndrome Study Group Rating Scale (IRLS), the Restless Legs Syndrome-6 Scale, and then the Brief International Cognitive Assessment for Multiple Sclerosis battery consisting of the Symbol Digit Modalities Test; California Verbal Learning Test, Second Edition; and Brief Visuospatial Memory Test-Revised.

Results: Nonparametric bivariate correlations indicated that worse IRLS total severity was associated with slower processing speed (ρ = -0.42), worse verbal memory (ρ = -0.63), and worse visual memory (ρ = -0.61); worse RLS severity at falling asleep was associated with worse verbal memory (ρ = -0.45) and worse visual memory (ρ = -0.55); and worse RLS severity during the day while active was associated with slower processing speed (ρ = -0.58), worse verbal memory (ρ = -0.52), and worse visual memory (ρ = -0.60).

Conclusions: These results suggest that those with more severe RLS, including worse symptoms at falling asleep and during the day while active, might experience worse cognitive function, particularly processing speed and memory. Future research should evaluate whether treatment of RLS symptoms can offer new opportunities for managing cognitive dysfunction in adults with MS.

Keywords: cognitive functioning; multiple sclerosis; restless legs syndrome; sleep.