Abstract
Non-motor symptoms are common in patients with newly diagnosed Parkinson’s disease (PD), and some even predate the emergence of the classic motor features. The premotor phase of PD is characterized by several important non-motor features, including constipation, olfactory dysfunction, REM sleep behavior disorder (RBD), depression, etc. The basis of this prodromal stage is that the pathological process related to Lewy bodies, may start outside of the substantia nigra. We investigated 469 Japanese PD patients in our multicenter study, using the Japanese version of the RBD screening questionnaire. Probable RBD was detected in 146 patients (31%) and the RBD symptoms of 53 patients preceded the onset of PD motor symptoms. With the probable exception of RBD, non-motor clinical markers can be sensitive for an impending diagnosis of PD, but these features are common and non-specific. The combination of non-motor clinical markers and more specific markers (e.g., imaging or genetic markers) may achieve sufficient utility in PD diagnosis and prediction in future. Being able to diagnose that a patient has PD at an earlier time point than is currently possible, would be allowed to introduce potential disease-modifying therapies at a time when it could have fundamental and long-lasting effects.
