Sleep Apnea Syndrome in Patients with Idiopathic REM Sleep Behavior Disorder and Risk of Neurodegeneration

Abstract Background Idiopathic REM sleep behavior disorder (iRBD) is a prodromal manifestation of synucleinopathies. The comorbidity of iRBD and sleep apnea syndrome (SAS) may have significant clinical implications. This work aimed to evaluate the relationship between SAS and risk of parkinsonism or cognitive impairment (CI) development in patients with iRBD. Methods Patients with a confirmed diagnosis of iRBD were enrolled. SAS was evaluated by polysomnography. The presence of parkinsonism and CI was determined at follow-up visits performed every 12 months. Results SAS was diagnosed in 79.5% subjects with iRDB. 63.6% suffered moderate-to-severe sleep apnea and were indicated for positive airway pressure (PAP) therapy. After a median follow-up period of 4 years, 47.7% developed a CI and 31.8% parkinsonism. In binary regression analysis, older age of iRBD onset (OR: 1.134, 95% CI: 1.025–1.254, p = 0.015) was independent contributor in a model predicting parkinsonism. Similarly, proportion of REM sleep (OR: 0.850, 95% CI: 0.743–0.972, p = 0.017) and indication of PAP therapy (OR: 0.115, 95% CI: 0.015–0.869, p = 0.036) were inversely associated with parkinsonism. In a model predicting CI, higher daytime sleepiness according to Epworth Sleepiness Scale (OR: 1.230, 95% CI: 1.020–1.484, p = 0.031) and higher age at iRBD onset (OR: 1.137, 95% CI: 1.037–1.247, p = 0.006) were the only independent contributors. Conclusion We found a high prevalence of SAS in patients with iRBD. Indication of PAP therapy in patients with moderate-to-severe SAS could reduce the risk of parkinsonism development in patients with iRBD.