Not all that goes “bump in the night” is RLS

Parkinson disease (PD) and restless legs syndrome (RLS)¹ have few clinical features in common, but they both typically respond to dopaminergic drugs. Current evidence suggests that idiopathic RLS is not a significant risk factor for developing PD. Whether “true” RLS exists in PD, is more prevalent in PD than in the general population, and possibly results from dopaminergic augmentation is a recent matter of debate.

Eleven cross-sectional studies examined the frequency of RLS symptoms in patients with PD. This frequency ranges from 3% to 16% in Asia, 11% to 24% in Europe, and is estimated to be 20% in the United States.^2,–,5 Except for a 50%, nonreplicated frequency in Brazil, the 10%–24% frequency is quite homogeneous among countries, provided than one takes into account the lower prevalence of primary RLS in Asia compared to Europe and America. These studies suggest that RLS is slightly more frequent in PD than in the same ethnicity-, age- and gender-matched population; however, these studies were performed in movement disorders clinics, which selects for patients with more advanced PD already treated with dopaminergic drugs.

The study by Gjerstad et al.⁶ in this issue of Neurology® nicely avoids these limitations. It is the first study to examine the prevalence of RLS symptoms in a sample of 200 …