Clinical characteristics of newly diagnosed Parkinson's disease patients included in the longitudinal BIO-PD study
Abstract
Aim: The aim of this study was to describe the protocol of the longitudinal observational study "Biomarkers of Parkinson's disease" (BIO-PD) and provide clinical characteristics of newly diagnosed Parkinson's disease (PD) patients enrolled in the BIO-PD study to date. Methods: Treatment-naive PD patients diagnosed according to the Movement Disorders Society clinical diagnostic criteria with abnormal finding on dopamine transporter SPECT as well as healthy controls were enrolled in the study.
Baseline examination included brain MRI, structured interview, Movement Disorders Society-Unified PD Rating Scale (MDS-UPDRS), video-polysomnography, transcranial sonography, olfactory testing, visual color sensitivity, a battery of neurophysiological tests, detailed cognitive testing, a comprehensive set of questionnaires as well as sampling of biofluids. Results: As of July 2020, 95 PD patients (37 females, mean age 61.0 [SD = 12.4] years, mean symptom duration 1.9 [1.7] years) and 57 healthy controls (15 females, mean age 62.2 [9.4] years) were included in the study.
Compared to controls, PD patients were more likely to be never smokers (P = 0.02) and to have a history of anxiety or depression disorder (P = 0.02), and constipation (P = 0.002). In addition, PD patients had worse scores in the visual color sensitivity (Farnsworth-Munsell Hue 100) test (P = 0.002), MDS-UPDRS motor score, Beck depression inventory-II, State-Trait Anxiety Inventory X1/ X2, Scales for Outcomes in PD-Autonomic questionnaire (SCOPA-AUT), University of Pennsylvania Smell Identification Test, and more frequent substantia nigra hyperechogenicity on transcranial sonography (P < 0.001 for all tests).
The frequencies of symptoms and abnormal findings in PD patients were as follows: hyposmia 82.4%, substantia nigra hyperechogenicity 75.4%, history of anxiety or depression disorder 29.5%, constipation 22.1%, and REM (rapid eye movement) sleep behavior disorder 22%. Conclusion: Baseline characteristics of patients enrolled in the BIO-PD study are comparable to other de novo PD cohorts, indicating that it is a representative sample of PD patients.
Hyposmia is the most prevalent non-motor abnormality in newly diagnosed PD patients and is thus a suitable diagnostic marker for early PD