Work

0660 Higher Amounts of REM Sleep without Atonia Predict Phenoconversion To Defined Neurodegenerative Disorders in Idiopathic REM Sleep Behavior Disorder

Year: 2018

Type: conference-abstract

Abstract: Idiopathic REM sleep behavior disorder (iRBD) is a manifestation of prodromal neurodegenerative disease in most older adults. However, biomarkers are needed to predict individualized risk of phenoconversion for accurate prognostication and use in future neuroprotective clinical trials. Whether polysomnographic REM sleep without atonia (RSWA) predicts phenoconversion in iRBD remains uncertain. We aimed to determine whether amount of RSWA on presenting polysomnography (PSG) was predictive of phenoconversion in iRBD. We analyzed amount of RSWA in 60 iRBD patients who underwent PSG between 2008–2012 at Mayo Clinic. Manual phasic, tonic, and “any” muscle activity and the automated REM atonia index (RAI) were analyzed in the submentalis (SM) muscle; phasic and “any” muscle activity were analyzed in the anterior tibialis (AT) muscle. We then identified patients who developed parkinsonism or mild cognitive impairment (MCI) during at least 3 years follow-up subsequent to PSG. Chi square analysis was used for categorical variables while Wilcoxon rank sum tests were performed for continuous variables. Twenty-six (43%) patients developed parkinsonism (n=13) or cognitive impairment (n=13). Phenoconverters were older than non-phenoconverters at iRBD diagnosis (p=0.02). Time to phenoconversion following iRBD diagnosis was 3.9 ± 2.5 years. Initial PSG RSWA was significantly higher in iRBD phenoconverters than in non-converters, with SM RAI (0.58 vs 0.74, p=0.027), SM “any” (44% vs 30%, p=0.05), SM tonic (19% vs 9% p=0.04), AT phasic (40% vs 30%, p=0.026), SM+AT phasic (58% vs 45%, p=0.016) and SM+AT “any” (65% vs 50%, p=0.01). RSWA was significantly higher in motor, but not in combined motor/cognitive or pure cognitive syndrome phenoconverters. Patients with iRBD who developed a defined neurodegenerative disorder had higher amounts of polysomnographic RSWA at iRBD diagnosis compared to those who remained disease-free, driven by motor but not cognitive syndrome phenoconverters. Our findings suggest amount of RSWA at iRBD diagnosis is a useful biomarker to identify risk for phenoconversion. Mayo Clinic CCaTS and Parkinson’s Disease Foundation-American Parkinson Disease Association Summer Student Fellowship, PDF-APDA-SFW- 1656.

Source: SLEEP

DOI: 10.1093/sleep/zsy061.659