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Heterogeneity of Parkinson’s disease in the early clinical stages using a data driven approach

¹ Cambridge Centre for Brain Repair, University of Cambridge; and Department of Neurology, University of Cambridge, UK
² Department of Psychiatry, University of Cambridge, UK
³ Department of Experimental Psychology, University of Cambridge, UK
⁴ Medical Research Council Cognition and Brain Sciences Unit, Cambridge, UK

Correspondence to:
Correspondence to:
S J G Lewis
Cambridge Centre for Brain Repair, Forvie Site, Addenbrooke’s Hospital, Cambridge, CB2 2PY, UK; sjgl2{at}wbic.cam.ac.uk

Objective: To investigate the heterogeneity of idiopathic Parkinson’s disease (PD) in a data driven manner among a cohort of patients in the early clinical stages of the disease meeting established diagnostic criteria.

Methods: Data on demographic, motor, mood, and cognitive measures were collected from 120 consecutive patients in the early stages of PD (Hoehn and Yahr I–III) attending a specialist PD research clinic. Statistical cluster analysis of the data allowed the existence of the patient subgroups generated to be explored.

Results: The analysis revealed four main subgroups: (a) patients with a younger disease onset; (b) a tremor dominant subgroup of patients; (c) a non-tremor dominant subgroup with significant levels of cognitive impairment and mild depression; and (d) a subgroup with rapid disease progression but no cognitive impairment.

Conclusions: This study complements and extends previous research by using a data driven approach to define the clinical heterogeneity of early PD. The approach adopted in this study for the identification of subgroups of patients within Parkinson’s disease has important implications for generating testable hypotheses on defining the heterogeneity of this common condition and its aetiopathological basis and thus its treatment.

Abbreviations: BDI, Beck depression inventory; MMSE, Mini Mental State Examination; NART, National Adult Reading Test; PD, Parkinson’s disease; PRM, pattern recognition memory; TOL, Tower of London (test); UPDRS, Unified Parkinson’s Disease Rating Scale

Keywords: Parkinson’s disease; heterogeneity; cluster analysis

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