Restless leg syndrome carries increased risk of Parkinson’s disease

Patients with restless leg syndrome (RLS) face a heightened risk of developing Parkinson’s disease (PD), particularly those not receiving treatment with dopamine agonists (DAs), as shown in a retrospective study.

Researchers used data from the Korean National Health Insurance Service Sample Cohort. They matched 9,919 patients with RLS (mean age 50.3 years, 62.8 percent female) to 9,919 controls without RLS (mean age 50.1 years, 62.8 percent female).

The main outcome was the development of PD, assessed in the RLS vs control groups. The outcome was also evaluated among RLS patients who were treated with DAs (n=3,077) vs those who did not receive DAs (n=6,842).

PD occurred in 1.6 percent of participants in the RLS group vs 1 percent of those in the control group. At the prespecified time horizon of 15 years, the restricted mean survival time (RMST) to PD diagnosis was 14.88 years in the RLS group vs 14.93 years in the control group, for a difference of −0.05 years (95 percent confidence interval [CI], –0.07 to –0.03).

Compared with the control group, the subset of participants who did not receive DA in the RLS group had a markedly higher incidence of PD (2.1 percent) and shorter RMST to PD diagnosis (difference, –0.09 years, 95 percent CI, –0.12 to –0.06). Conversely, the subset of DA-treated participants in the RLS group had a lower incidence of PD (0.5 percent) and a significantly longer RMST to PD diagnosis (difference, 0.03 years, 95 percent CI, 0.01–0.06).

The present data point to a pathophysiological connection between RLS and PD that may involve mechanisms beyond the dopaminergic pathway, the researchers said.