title: The P3a wave: A reliable neurophysiological measure of Parkinson's disease duration and severity.
abstract: OBJECTIVE
  The P3a is an event-related potential (ERP) associated with involuntary attention and dopaminergic function. As P3a is reduced at initial stages of Parkinson's disease (PD), our objective was to assess P3a as a possible marker of PD duration and severity.
  
  
  METHODS
  Fifty-five patients were analyzed, 28 of which were at Hoehn and Yahr severity stage 1; 14 at stage 2; and 13 at stage 3. Seventeen patients were free of antiparkinsonian medication. PD duration was defined as the number of years between the onset of motor symptoms and the date of this study. Twenty-four healthy subjects were included as controls. An involuntary attention paradigm was administered while a digital EEG was obtained.
  
  
  RESULTS
  The P3a amplitude was significantly lower in all PD groups compared to the control group (F(3,75)=5.10, p=0.003), especially for stages 2 (p=0.017) and 3 (p=0.008). A regression analysis showed that the disease duration predicted inversely the P3a (Fz channel amplitude: Coefficient=-0.148, p=0.006; Frontocentral amplitude: Coefficient=-0.125, p=0.003) after controlling for demographic and clinical variables, medication, general cognitive state, and depression.
  
  
  CONCLUSIONS
  This is the first study reporting P3a sensibility to PD duration and severity.
  
  
  CONCLUSIONS
  This ERP could represent a reliable biomarker of the disease progression.
authors: Neuropsychology Department, Instituto Nacional de Neurología y Neurocirugía Manuel Velasco Suárez (INNNMVS), Mexico. Electronic address: rodolfoso@hotmail.com.
authors: Rodolfo
authors: R
authors: Solís-Vivanco
authors: Neurodegenerative Diseases Laboratory, INNNMVS, Mexico; Abnormal Movements Clinic, INNNMVS, Mexico.
authors: Mayela
authors: M
authors: Rodríguez-Violante
authors: Neuropsychology Department, Instituto Nacional de Neurología y Neurocirugía Manuel Velasco Suárez (INNNMVS), Mexico.
authors: Yaneth
authors: Y
authors: Rodríguez-Agudelo
authors: Instituto Nacional de Salud Pública, Mexico.
authors: Astrid
authors: A
authors: Schilmann
authors: Abnormal Movements Clinic, INNNMVS, Mexico.
authors: Ulises
authors: U
authors: Rodríguez-Ortiz
authors: Behavioral and Cognitive Neurobiology Department, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Mexico.
authors: Josefina
authors: J
authors: Ricardo-Garcell
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers; D001921:Brain / Q000502:physiology; D016022:Case-Control Studies; D003071:Cognition / Q000502:physiology; D018450:Disease Progression; D004569:Electroencephalography; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009482:Neurophysiology / Q000379:methods; D010300:Parkinson Disease / Q000175:diagnosis* / Q000503:physiopathology*; D012044:Regression Analysis; D012720:Severity of Illness Index
chemical_list: D015415:Biomarkers
keywords: Biomarker; Duration; P3a; Parkinson’s disease; Severity