Comparison of Cognitive Function between Patients with Restless Legs Syndrome and Healthy Controls

Abstract

Recent studies have reported that moderate to severe restless legs syndrome (RLS) patients may have significant cognitive deficits, primarily in executive functioning, compared with healthy control subjects.1-4 Electrophysiological studies also support the existence of cognitive dysfunction in RLS patients. For example, a recent event-related potential (ERP) study showed that underlying cognitive dysfunction, associated with a working memory deficit characterized by increased reaction time and lower amplitude of the P300 component, was evident in patients with severe RLS.5,6 In contrast, other studies found no difference in cognitive function between RLS patients and controls. RLS subjects performed better than sleep-restricted controls on a test of verbal fluency.7 In middle-aged and elderly subjects, individuals with mild RLS were found to have no differences in multiple domains of cognitive functioning when compared to those without RLS.8,9 This discrepancy may be attributable to several factors, such as differences in study samples, the use of different age groups (patients of middle vs. older age), the types of neuropsychological tests administered (full batteries vs. selected tests of frontal function), and medication effects (unmedicated vs. medicated). It has been reported that comorbid psychiatric conditions such as depression and anxiety are common in patients with RLS.10-12 Epidemiological studies report a 2to 4-fold risk of a deReceived: November 22, 2014 Revised: December 10, 2014 Accepted: December 15, 2014