Rapid eye movement sleep behavior disorder: modern concept and Parkinson’s disease correlation

This review describes the association between rapid eye movement (REM) sleep behavior disorder (RBD) and synucleinopathies, primarily Parkinson's disease. This article reviews the diagnostic criteria, the epidemiology of RBDs, their pathogenesis, and their association with early non-motor symptoms. The data are presented to assess the risk of phenoconversion of RBDs to Parkinson's disease or other synucleinopathies such as Lewy body dementia and multiple system atrophy. A prodromal period of RBDs may precede synucleinopathies years or decades before potential manifestation of motor, cognitive, or autonomic disorders, and this may be important for initiating the neuroprotective therapy. Other causes of RBDs are also reviewed.