Critically appraised topic on Rapid Eye Movement Behavior Disorder: From protein misfolding processes to clinical pathophysiology and conversion to neurodegenerative disorders

Background REM Behavior Disorder (RBD) is considered one of most powerful prodromal condition in different neurodegenerative disorders, mainly alpha-synucleinopathies. A large amount of research recently explored this relationship. Objective and Design The present critically appraised review undertakes this topic, from the perspective of the pathogenetic interplay between clinical manifestations in RBD patients and the misfolding processes that characterize neurodegeneration. In particular, evidence in favor and against the role of RBD as a biomarker of neurodegeneration is discussed. Results and Conclusion The selected papers were functional to structure the review into three main sections: 1) Protein misfolding in neurodegenerative disorders with focus on alpha-synuclein; 2) Clinical features, diagnosis, and pathophysiology of RBD; 3) RBD as a clinical biomarker of protein misfolding. Data herein highlights the current knowledge and the areas of uncertainties in the relationship between RBD and neurodegenerative disorders; we went through preclinical, prodromal and clinical stages of neurodegenerative processes as a useful reference for clinicians involved in brain pathological aging and future research in this field.