Clinical clusters and dopaminergic dysfunction in de-novo Parkinson disease. (July 2016)

• Record Type: Journal Article
• Authors: Erro, Roberto; Picillo, Marina; Vitale, Carmine; Palladino, Raffaele; Amboni, Marianna; Moccia, Marcello; Pellecchia, Maria Teresa; Barone, Paolo
• Is Part Of: Parkinsonism & related disorders. Volume 28(2016)
• Page Start: 137
• Page End: 140
• Publication Date: 2016-07
• Subjects: Parkinson -- Subtypes -- Clusters -- Non-motor -- Heterogeneity; Parkinson's disease -- Periodicals; Movement disorders -- Periodicals; Movement Disorders -- Periodicals; Nerve Degeneration -- Periodicals; Nervous System Diseases -- Periodicals; Parkinson Disease -- Periodicals; Tremor -- Periodicals; Parkinson, Maladie de -- Périodiques; Parkinson's disease; 616.833
• DOI: 10.1016/j.parkreldis.2016.04.026
• Languages: English
• ISSNs: 1353-8020

Abstract

Abstract: Background: The heterogeneity of PD suggests the existence of different subtypes. While some motor clusters have been consistently identified, little is known about non-motor PD subtypes and motor-non-motor interplay. Research in this regard has produced somewhat contradictory results, which might be biased by the inclusion of treated patients. Patients and methods: We performed a non-hierarchical cluster analysis using both motor and non-motor data on 398 newly diagnosed untreated PD patients enrolled in the Parkinson's Progressive Marker Initiative (PPMI) study. We further evaluated whether dopaminergic dysfunction, as measured by 123 [I]-FP-CIT SPECT scan, could explain, at least partially, the observed difference between the clusters. Results: Three clusters were identified. Group 1 was characterized by the lowest motor and non-motor burden, whereas group 2 and 3 had similar motor disability, but different non-motor involvement, especially with regards to apathy and hallucinations. 123 [I]-FP-CIT binding values paralleled motor disability burden among the 3 clusters, but further multivariate analyses also revealed a negative correlation with depression. Discussion: Our results confirm the motor as well as non-motor heterogeneity of PD, suggesting the existence of 3 different subtypes. Dopaminergic dysfunction only marginally explains the non-motor variability of PD. Identification of such clusters can have important implications for generating novel pathophysiological hypotheses and therapeutic strategies. Highlights: Non-motor symptoms in PD are as relevant as motor disturbances. PD patients are very heterogeneous also in terms of non-motor symptoms. Three main PD clusters can be identified when considering both motor and non-motor symptoms. Dopaminergic denervation poorly explains (motor-non-motor) heterogeneity of PD.