Pre-conference workshop: Visual mismatch negativity
Tuesday, Sep 8, 2015
The diagnostic and prognostic value of visual evoked potentials and vMMN in Alzheimer’s disease and mild cognitive impairment
1School of Experimental Psychology, University of Bristol, Bristol, United Kingdom
2Psychology, Swansea University, United Kingdom
3Institute of Behavioural Sciences, University of Helsinki, Finland
Cortical visual association areas are highly vulnerable to Alzheimer’s disease (AD) microscopic pathology and visual evoked potentials (VEPs) provide the tools to examine the functional integrity of these areas. Visual mismatch negativity (vMMN), previously shown to be maintained in healthy ageing (Stothart et al. 2012, Neurobiology of Aging), may potentially be a useful tool to examine such processes in clinical populations.
Cross Sectional study
We used VEPs to investigate the visual processing of healthy older adults (n=26), patients with amnestic Mild Cognitive Impairment (aMCI) (n=26) and AD patients (n=20) in a visual oddball paradigm. AD patients showed a significant reduction of P1 and N1 VEP amplitudes and a reduction in vMMN associated with the degree of cognitive impairment. aMCI patients showed a reduction in N1 amplitude and an absence of vMMN at a group level. Further investigation showed a high degree of group heterogeneity in the evoked potentials of the aMCI group compared to both healthy ageing and AD. Changes in VEPs in AD may reflect the microstructural AD pathology typically found in the extrastriate cortex and vMMN may be a useful objective marker of cognitive decline in AD.
Longitudinal follow-up of aMCI patients
In three years 12 aMCI patients had converted to Alzheimer’s disease, of which 8 were able to attend a re-test EEG session. Data on the diagnostic and prognostic value of VEPs and vMMN in dementia will be discussed.