Abstract
BACKGROUND: Parkinsonism is defined by motor features (tremor, bradykinesia, rigidity, and postural instability). Accompanying non-motor features (e.g. cognitive, autonomic, sleep disturbances) are underrecognized and undertreated. We hypothesized that clinical patterns occurring in early, medication-naïve Parkinsonism are distinguished by features such as tremor, sleep, autonomic, and cognitive dysfunction. METHODS: Clinical and neuroimaging data were obtained in the Parkinson's Progression Marker Initiative. Group comparisons of Parkinsonism with dopaminergic deficits (PDD) (n = 388), controls (n = 196), and Parkinsonism with scans without evidence of dopaminergic deficits (n = 64) were done with ANOVA, chi-square, and post-hoc pairwise tests. To examine clinical patterns within the PDD group, k-means clustering was performed with non-motor or motor features, or both. RESULTS: Among PDD, 4 non-motor patterns (% of PDD) (impulsive (14.9%), sleep-autonomic (22.9%), cognitive-olfactory (18.0%), and mild (44.1%)), 4 motor patterns (tremor plus bradykinesia (56.2%), tremor without bradykinesia (16.2%), postural instability (6.7%) and no tremor (20.9%)) and 5 combined motor/non-motor patterns (tremor with bradykinesia (42.3%), tremor without bradykinesia (15.5%), no tremor and mild non-motor features (17.0%), postural instability with sleep-autonomic disturbances (6.7%) and oldest onset cognitive-olfactory (18.6%)) were observed. CONCLUSIONS: To our knowledge, this is the first description of non-motor clinical patterns in early, medication-naïve Parkinsonism, suggesting that such features are intrinsic to Parkinsonian disorders.