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

Background and Objective Studies regarding cognitive function in patients with restless legs syndrome (RLS) show inconsistent results, although comorbid psychiatric conditions including depression and anxiety are common in these patients. We compared cognitive performance and depression symptoms between drug-naïve RLS patients and healthy controls, in order to determine whether the depression symptoms that result from RLS affect cognitive function. Methods Drug-naïve RLS patients (n = 15) and age-matched controls (n = 17) were enrolled in the study. They completed clinical interviews, sleep questionnaires, and a neuropsychological assessment battery that measured multiple cognitive domains including attention, language ability, memory, and executive function. Depression was measured using the Beck Depression Inventory-II. Statistical analyses included chi-square and non-parametric Mann-Whitney U tests, and Spearman correlations. Results Restless legs syndrome patients performed better than controls on tests of verbal memory and category word fluency (animal) (p < 0.05). The RLS group had significantly higher depression scores than controls (p = 0.005). Depression scores for the RLS patients showed significant correlations with restless legs symptoms and several measures of sleep quality. There were no significant differences in cognitive function between patients with moderate to severe depression (n = 6) and those without depression (n = 6). Conclusions Our study did not confirm that symptoms of RLS were associated with cognitive dysfunction. In addition, depression symptoms had little impact on cognitive function, but were independently associated with symptoms of RLS regardless of cognitive function