Restless legs syndrome in Korean patients with drug-naïve Parkinson's disease: a nation-wide study

Abstract

Background: Restless legs syndrome is a common neurologic disorder, and there is increasing evidence for a dopaminergic link between Parkinson's disease and restless legs syndrome. However, most previous studies did not take into account the effects of dopaminergic medication. We conducted a nation-wide, cross-sectional study to determine the prevalence and clinical characteristics of restless legs syndrome in Korean drug-naïve Parkinson's disease patients.

Methods: One hundred and fifty-one drug-naïve patients with Parkinson's disease were enrolled from 18 centers in South Korea over the course of one year. Clinical profiles of parkinsonism, restless legs syndrome, psychiatric symptoms, and laboratory data were collected. The findings of subjects with and without restless legs syndrome were compared.

Results: The prevalence of restless legs syndrome in drug-naïve patients with Parkinson's disease was 16.5%. Subjects with restless legs syndrome had a higher mean Hoehn and Yahr stage and more severe limb parkinsonism, especially tremor. There was, however, no difference in iron metabolism between patients with and without restless legs syndrome. Analysis demonstrated that Beck's depression inventory score was associated with the severity of restless legs syndrome.

Conclusion: Our study demonstrated an increased prevalence of restless leg syndrome in drug-naïve patients with Parkinson's disease than in the general population. Based on the association between parkinsonism and restless legs syndrome, and the unique characteristics of restless legs syndrome in patients with Parkinson's disease, we suggest that the pathophysiology of restless legs syndrome in Parkinson's disease differs from that in patients without Parkinson's disease.