title: Early visual evoked potentials and mismatch negativity in Alzheimer's disease and mild cognitive impairment.
abstract: BACKGROUND
  Cortical visual association areas are highly vulnerable to Alzheimer's disease (AD) microscopic pathology. Visual evoked potentials (VEPs) provide the tools to examine the functional integrity of these areas and may provide useful indicators of early disease progression.
  
  
  OBJECTIVE
  To assess the functional integrity of visual association area processing in AD and amnestic mild cognitive impairment (aMCI) using VEPs.
  
  
  METHODS
  We investigated the visual processing of healthy older adults (n = 26), AD (n = 20), and aMCI (n = 25) patients in a visual oddball paradigm designed to elicit the visual P1, N1, and visual mismatch negativity (vMMN).
  
  
  RESULTS
  AD patients showed a significant reduction of P1 and N1 VEP amplitudes and aMCI patients showed a reduction in N1 amplitude compared to healthy older adults. P1 amplitude in response to deviant stimuli and vMMN amplitude were found to be associated with the degree of cognitive impairment as measured by the Mini-Mental State Examination.
  
  
  CONCLUSIONS
  Changes in VEPs in AD may be a consequence of the microscopic AD pathology typically found in the extrastriate cortex. Neural measures of visual processing may help to better characterize subgroups of aMCI patients likely to develop AD. Additionally, VEPs and vMMN may provide objective markers of cognitive decline.
authors.affiliation: School of Experimental Psychology, University of Bristol, Bristol, UK.
authors.forename: George
authors.initials: G
authors.lastname: Stothart
authors.affiliation: School of Experimental Psychology, University of Bristol, Bristol, UK.
authors.forename: Nina
authors.initials: N
authors.lastname: Kazanina
authors.affiliation: Department of Psychology, University of Tartu, Estonia Center of Functionally Integrative Neuroscience, University of Århus, Denmark Institute of Behavioural Sciences, University of Helsinki, Finland.
authors.forename: Risto
authors.initials: R
authors.lastname: Näätänen
authors.affiliation: South Gloucestershire Memory Service, Avon and Wiltshire Mental Health Partnership, Bristol, UK.
authors.forename: Judy
authors.initials: J
authors.lastname: Haworth
authors.affiliation: Department of Psychology, Swansea University, Singleton Park, Swansea, Wales, UK.
authors.forename: Andrea
authors.initials: A
authors.lastname: Tales
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology*; D060825:Cognitive Dysfunction / Q000503:physiopathology*; D004569:Electroencephalography; D005074:Evoked Potentials, Visual; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D014796:Visual Perception / Q000502:physiology*
keywords: Alzheimer's disease; electroencephalography; mild cognitive impairment; mismatch negativity; visual evoked potentials