REM sleep behavior disorder is absent in de novo parkinson disease patients with parkin mutations: a report from the DENOPA cohort

Abstract

Introduction We are currently prospectively investigating non-motor symptoms of 159 at baseline de novo patients with Parkinson disease (PD) and 110 healthy controls matched for age and gender in a single-centre cohort study (DeNoPa cohort). In this substudy we analyzed the occurrence of REM sleep behaviour disorder (RBD) in de novo PD patients with heterozygous Parkin mutations. Materials and methods Video-supported PSG (vPSG) was performed on two consecutive nights. All REM phases were reviewed in real time video analysis for identification of RBD. The night with the most severe RBD manifestation was used for further analysis of sleep architecture. If no RBD was registered in REM sleep, the second night was analyzed. REM without atonia (RWA) was measured as any muscle activity on chin EMG in three second mini epochs with a duration exceeding 0.1 s and an amplitude greater than double baseline and calculated as percent of total REM. Results We identified 6/159 (4%) de novo PD patients with heterozygous Parkin mutations. All six were male and not related. Mean age was 63.3 ± 11.5 years. (range 48–76), compared to 65 ± 10 (40–85) in the non-Parkin group. Hoehn & Yahr stage was determined at 1.3 ± 0.27 (range 1.0–1.5), compared to 1.8 ± 0.7 (1–3) in the non-Parkin group. None of the Parkin mutation carriers was identified with RBD, whereas 40/152 (26%) non-Parkin PD patients with valid vPSG showed RBD according to current diagnostic criteria as defined by ICSD 2. RWA values were measured at 5.9 ± 3.9% (range 0.7–11.1%) in the Parkin group, which corresponded to 6 ± 8% (0–51%) in the non-Parkin PD group without RBD. Two Parkin PD patients had a positive history for potential RBD. However, RWA was determined at 0.7% and 5.1% in these two study subjects. Conclusion RBD is absent in PD subjects with heterozygous Parkin mutations. This finding implies a crucial role of alpha- synuclein misprocessing in the pathogenesis of RBD. Acknowledgements The authors thank T.Wicke, E. Lang and N. Drescher for technical assistance.