Objective: This study explores the risk and correlates of leg restlessness in drug-naive patients with Parkinson disease (PD) as compared to control subjects matched for age and gender.
Methods: A total of 200 drug-naive patients with early, unmedicated PD derived from a population-based incident cohort and 173 age- and gender-matched control subjects were assessed for leg restlessness by structured interviews, clinical examination, and blood samples. All subjects were Caucasian. Restless legs syndrome (RLS) was diagnosed according to the essential diagnostic criteria.
Results: More patients (81 of 200, 40.5%) than controls (31 of 173, 17.9%) reported leg restlessness (p < 0.001). Thirty-one (15.5%) of these patients with PD and 16 (9.2%) control subjects met RLS criteria (p = 0.07). A total of 21 (12.5%) patients and 12 (6.9%) controls with RLS remained after the exclusion of potential RLS mimics and 26 patients vs 10 control subjects with leg motor restlessness (LMR), leading to a relative risk for RLS of 1.76 (95% confidence interval [CI] 0.90-3.43, p = 0.089) and 2.84 for LMR (95% CI 1.43-5.61, p = 0.001) in PD. Except for increased sleep disturbances in patients with RLS and increased Montgomery and Åsberg Depression Rating Scale scores for patients with RLS or LMR there were no other major differences in relevant blood tests, motor or cognitive function between PD with and without RLS or LMR.
Conclusion: LMR and not RLS occurs with a near 3-fold higher risk as compared to controls in early PD. The findings underline a need for more accurate assessments of RLS in PD and support the notion that RLS and PD are different entities.