Cognitive event-related potentials: biomarkers of synaptic dysfunction across the stages of Alzheimer's disease

Abstract

Cognitive event-related brain potential (ERP) studies of decision-making and attention, language, and memory impairments in Alzheimer's disease (AD) and mild cognitive impairment (MCI) are reviewed. Circumscribed lesions of the medial temporal lobe (MTL), as may be the case in individuals with amnestic MCI, generally produce altered plasticity of the late positive P600 component, with relative sparing of earlier sensory ERP components. However, as the neuropathology of AD extends to neocortical association areas, abnormalities of the P300 and N400 (and perhaps even P50) become more common. Critically, ERP studies of individuals at risk for AD may reveal neurophysiological changes prior to clinical deficits, which could advance the early detection and diagnosis of "presymptomatic AD".

Figures

Fig. 1

Spherical spline topographic maps illustrate the incongruous word repetition effect (ERPs to new minus old semantically incongruous words) in consecutive 50 msec epochs for normal old (left) and MCI stable (left middle) groups at year 1, and MCI converters at year 1 (right middle) and year 2 (right).

Fig. 2

Grand average ERPs to initial (dash line) and repeated (solid line) presentation of congruous words in “robust” normal elderly (RNE) (top row) and Preclinical AD patients (bottom).