Does idiopathic restless legs syndrome delay onset and reduce severity of Parkinson's disease: a pilot study.

Parkinson's disease (PD) populations show that about 20% of patients meet criteria for restless legs syndrome (RLS). Nevertheless, pathological differences suggest RLS may actually prevent PD. Over 15 years, we collected patients with idiopathic RLS preceding onset of PD, as defined by onset of RLS greater than 5 years before motor symptoms of PD, or a family history of RLS and onset of RLS at least 1 year before PD. We then compared these to a control group of PD without RLS for demographics, age of onset, motor progression, dyskinesia, L-dopa equivalent dose, and PD phenotype at onset. The RLS/PD group (N = 36) had 13 females with 18 having a positive family history of RLS and six with a family history of PD. The PD control group (N = 36) had 10 females with 1 having a family history of RLS and nine with family history of PD. Age at motor onset of PD in the RLS/PD was older (64.15 ± 6.44 years vs. 56.81 ± 10.68) than for controls with PD (p < 0.001). After correcting for other risk factors and duration of follow-up, patients with idiopathic PD (21/36) developed dyskinesia more than RLS/PD (4/32) at final visit (p = 0.01). Our data suggest that idiopathic RLS may delay the onset of PD, reduce dyskinesia occurrence, and possibly reduce progression of PD.