title: Study of levodopa response in Parkinson's disease: Observations on rates of motor progression.
abstract: BACKGROUND
  It is important to understand how the rate of motor progression in PD relates to dopaminergic treatment.
  
  
  METHODS
  The methods for this study comprised prospective defined off state measurements of the levodopa response at 3-year intervals over a mean 13.3-year period in 34 patients enrolled before treatment initiation.
  
  
  RESULTS
  Despite worsening of on and off scores, the magnitude of the l-dopa short-duration response is maintained as the disease progresses. A linear mixed-effects regression analysis of off phase motor scores showed a yearly deterioration of 2.3% of the maximum disability score. Greater motor disability at the commencement of treatment was an independent predictor of faster progression. Demented patients had worse motor function than those without dementia (P = 0.02), and motor deficit appeared to accelerate toward the end of the disease course in patients who had died.
  
  
  CONCLUSIONS
  These observations should inform clinical trial design for drugs with possible neuroprotective properties.
authors.affiliation: Neurosciences Department, Monash Medical Center, Clayton, Victoria, Australia.
authors.forename: Catherine
authors.initials: C
authors.lastname: Ding
authors.affiliation: Neurosciences Department, Monash Medical Center, Clayton, Victoria, Australia.
authors.forename: Ganga
authors.initials: G
authors.lastname: Ganesvaran
authors.affiliation: Neurosciences Department, Monash Medical Center, Clayton, Victoria, Australia.
authors.forename: Jane E
authors.initials: JE
authors.lastname: Alty
authors.affiliation: Neurosciences Department, Monash Medical Center, Clayton, Victoria, Australia.
authors.forename: Benjamin G
authors.initials: BG
authors.lastname: Clissold
authors.affiliation: Neurosciences Department, Monash Medical Center, Clayton, Victoria, Australia.
authors.forename: Craig D
authors.initials: CD
authors.lastname: McColl
authors.affiliation: Neurosciences Department, Monash Medical Center, Clayton, Victoria, Australia.
authors.forename: Katrina A
authors.initials: KA
authors.lastname: Reardon
authors.affiliation: Neurosciences Department, Monash Medical Center, Clayton, Victoria, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Schiff
authors.affiliation: Neurosciences Department, Monash Medical Center, Clayton, Victoria, Australia.|Stroke and Ageing Research Group, Vascular Brain Aging Division, Department of Medicine, School of Clinical Sciences, Monash University, Melbourne, Victoria, Australia.|Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Velandai
authors.initials: V
authors.lastname: Srikanth
authors.affiliation: Neurosciences Department, Monash Medical Center, Clayton, Victoria, Australia.|Department of Medicine, Monash University, Clayton, Victoria, Australia.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Kempster
mesh_terms: D000368:Aged; D000978:Antiparkinson Agents / Q000008:administration & dosage / Q000494:pharmacology*; D003704:Dementia / Q000188:drug therapy* / Q000209:etiology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007980:Levodopa / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D010300:Parkinson Disease / Q000150:complications / Q000188:drug therapy*; D012720:Severity of Illness Index
chemical_list: D000978:Antiparkinson Agents; D007980:Levodopa
keywords: Parkinson's disease; dementia; levodopa; natural history