Auditory Event-Related Potentials in Different Types of Dementia

Abstract

Auditory event-related potentials were recorded in demented, drug-free patients with Huntington’s disease and Alzheimer’s disease, as well as in demented and nondemented patients with Parkinson’s disease, who were matched for age, duration and stage of the disease. The normal P3 latency at a given age was predicted by using an age regression equation that had been calculated on the basis of the findings in 42 normal adults. Using this procedure, a prolonged P3 latency was found in about two thirds of demented patients, irrespectively of the underlying disease. Although the prolonged P3 latency proved to be useful electrophysiological correlate of dementing illness, no differences were found between the observed groups in respect to other components of the auditory event-related potentials (N1 and P2).

Parkinson’s Dementia and Alzheimer’s Dementia: An Evoked Potential Comparison

“…The absence of significant parietal ERP P3 delay in the dementia groups compared with controls may either indicate that dementia does not significantly alter the underlying bas ic stimulus-updating/attention-allocation pro cess, or, more likely, that the overlap between advanced ageing (75+) and dementia effects on this process at an electrophysiological level is substantial. In any event, the finding of a significant ERP P3 latency delay associated with dementia is consistent with existing liter ature [9], The absence of a significant delay in the ERP N1 latency in association with PD dementia is consistent with published papers on this subject [11][12][13] subsequent to the ini tial paper by Goodin and Aminoff [10], The reasons for lack of concurrence with the find ings of Goodin and Aminoff are not clear, as the methodologies deployed in the present study and those described in the other papers on this subject are very similar. The differential flash-VEP N1 latency re duction associated with PD dementia is a more interesting finding, not reported in the literature to date.…”

“…A differential ERP N1 component delay in PD dementia is a conten tious finding, however. In follow-up studies attempting to replicate this finding, an N1 delay in demented PD patient groups com pared with AD groups has not been emergent [11][12][13], A differential flash visual evoked potential (VEP) P2 component latency delay may be a feature of AD, not present in patients with depression or non-demented individuals with cortical atrophy [14], This effect, coupled with an intact pattern-reversal VEP P I00 component latency has been noted in studies comparing elderly AD patients with controls [15,16]. The latency difference between the flash-VEP P2 and the pattern-reversal VEP P I00 is thus consistently increased in AD in these studies, this effect being considered to reflect pathological involvement of the parastriate visual association cortex, with relative sparing of the primary visual (striate) cortex in AD; positron emission tomographic studies [17] and autopsy [18] pathological analysis in AD support this view.…”

Does P3 Reflect Attentional or Memory Performances, or Cognition more Generally?

“…Measures of P3 latency and amplitude have been found to show high reliability in older adults (Pollock & Schneider, 1992). In that study, as well as in some other studies, the electrooculogram was not recorded (Filipovic et al 1990). Furthermore, in the present study, P3 was recorded at one site (Pz), and even though this site is known to provide maximal P3b, the results must be interpreted with some caution.…”

Semantic Processing of Spoken Words in Alzheimer's Disease: An Electrophysiological Study

“…N1 latency was signiªcantly different: N1 peaked earlier for the AD patients than for the controls. Previous studies on auditory ERPs support the view that N1 and P2 are usually similar in AD patients and controls (e.g., Filipovic, Kostic, Sternic, Marinkovic, & Ocic, 1990). The only difference that consistently appeared between the groups was the topographical distribution of peak latencies.…”