title: Levodopa peak response time reflects severity of dopamine neuron loss in Parkinson's disease.
abstract: We measured the time to peak antiparkinson response following injection of levodopa or apomorphine in 57 patients with Parkinson's disease. The peak response time for levodopa fell from 53 +/- 6.5 minutes in patients at Hoehn and Yahr stage I-II, and 28 +/- 4.8 minutes in those at stage IV (p < 0.0005). There was a significant correlation between levodopa peak response time and symptom duration (r = 0.65; p < 0.0001), but there was no relation between apomorphine peak response time and measures of disease severity. Peak response time to levodopa appears to reflect predominantly the status of compensatory presynaptic dopaminergic mechanisms and thus may provide an index to the degree of dopamine neuron degeneration in parkinsonian patients.
authors.affiliation: Experimental Therapeutics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892.
authors.forename: Y H
authors.initials: YH
authors.lastname: Sohn
authors.forename: L V
authors.initials: LV
authors.lastname: Metman
authors.forename: D
authors.initials: D
authors.lastname: Bravi
authors.forename: I
authors.initials: I
authors.lastname: Linfante
authors.forename: A
authors.initials: A
authors.lastname: Aotsuka
authors.forename: M M
authors.initials: MM
authors.lastname: Mouradian
authors.forename: T N
authors.initials: TN
authors.lastname: Chase
mesh_terms: D001058:Apomorphine / Q000627:therapeutic use; D002470:Cell Survival; D004298:Dopamine / Q000378:metabolism*; D005260:Female; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009474:Neurons / Q000378:metabolism* / Q000473:pathology / Q000502:physiology; D010300:Parkinson Disease / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology*; D011930:Reaction Time
chemical_list: D007980:Levodopa; D001058:Apomorphine; D004298:Dopamine