title: Heterogeneity of Parkinson's disease in the early clinical stages using a data driven approach.
abstract: 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.
authors.affiliation: Cambridge Centre for Brain Repair, Forvie Site, Addenbrooke's Hospital, Cambridge, CB2 2PY, UK. sjgl2@wbic.cam.ac.uk
authors.forename: S J G
authors.initials: SJ
authors.lastname: Lewis
authors.forename: T
authors.initials: T
authors.lastname: Foltynie
authors.forename: A D
authors.initials: AD
authors.lastname: Blackwell
authors.forename: T W
authors.initials: TW
authors.lastname: Robbins
authors.forename: A M
authors.initials: AM
authors.lastname: Owen
authors.forename: R A
authors.initials: RA
authors.lastname: Barker
mesh_terms: D017668:Age of Onset; D000368:Aged; D003072:Cognition Disorders / Q000145:classification / Q000209:etiology*; D015331:Cohort Studies; D003863:Depression; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000145:classification / Q000175:diagnosis* / Q000473:pathology*; D012016:Reference Values; D014202:Tremor / Q000209:etiology*
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