Kogan RV, Janzen A, Meles SK, et al. - In 20 patients with isolated rapid eye movement sleep behavior disorder, researchers sought to longitudinally examine Parkinson disease (PD)‐related brain pattern expression changes to ascertain if this technique can be used to analyze prodromal PD progression in these patients and to identify potential phenoconverters. Patients had two [¹⁸F]fluorodeoxyglucose‐PET brain scans about 3.7 years apart, as well as baseline and recurrent motor, cognitive, and olfactory testing within essentially the same time period. According to results, a greater shorter‐term risk for phenoconversion may be suggested by PD‐related brain pattern expression and higher score rate of change. In patients with isolated rapid eye movement sleep behavior disorder, the outcomes support the use of serial PD‐related brain pattern expression measurements as a prodromal PD progression biomarker.