Impulse control disorders in Parkinson's disease patients with RLS: a cross sectional-study

Background: Although dopamine replacement therapy is the main risk factor for the occurrence of Impulse Control Disorders (ICDs) in Parkinson's disease (PD), non-pharmacological risk factors for have also been identified in that population and sleep disorders could be part of them. Our objective is to determine whether Restless Legs Syndrome (RLS), that has been associated with more impulsive choices in general population regardless of dopaminergic therapy, could be associated with a specific psycho-behavioral profile and ICDs in PD.Methods: Eighty consecutive PD patients were screened for the presence of RLS in a cross-sectional study. Sleep features were evaluated during one video-polysomnography. The frequency of ICDs, according to standard criteria, together with a broad range of psycho-behavioral features using the Ardouin Scale of Behavior in PD, were compared in patients with RLS (PD-RLS, n = 30) versus without RLS (PD-nRLS, n = 50).Results: PD patients with RLS reported significantly more ICDs than those without RLS (50% versus 26%, p = 0.03), especially compulsive eating disorders, and a different psycho-behavioral profile with more hyperdopaminergic behaviors. There was no between group difference for total and dopamine agonists levodopa equivalent doses. However, age and durations of both disease and dopaminergic treatment were greater in the RLS group. Multivariate and propensity score analyses controlling for age, gender, total sleep time, disease severity, dose and duration of treatment, anxiety and depression showed that RLS was an independent predictor of ICDs in PD (OR = 5.91 [1.63; 22.1] and OR = 2.89 [1.63; 6.67] respectively).Conclusion: RLS per se could be a risk factor for impulsive behaviors in PD.