Predicting the conversion of rapid eye movement sleep behavior disorder to Parkinson disease: Research advances in predictive biomarkers

The identification of phenotypic conversion from rapid eye movement sleep behavior disorder to Parkinson disease remains constrained by the absence of objective indicators. This review systematically synthesizes the pathological mechanisms underlying such conversion, with particular emphasis on high-risk biomarkers predictive of phenotypic transition in rapid eye movement sleep behavior disorder. Key biomarkers discussed include pathological alpha‑synuclein, alterations in nucleic acid and protein expression profiles in biofluids, dopamine transporter abnormalities, changes in cerebral metabolic patterns, electroencephalographic frequency band shifts, and sleep microstructure indices during rapid eye movement sleep. These biomarkers exhibit varying degrees of predictive utility across distinct pathological stages of disease progression. Nevertheless, challenges persist, including inconsistent predictive specificity and insufficient standardization of assessment criteria. Moving forward, large‑scale longitudinal studies that integrate multimodal biomarkers will be essential to accurately identify high‑risk individuals, thereby enabling early detection and personalized intervention for Parkinson disease.