Journals of Gerontology Series A: Biological Sciences and Medical Sciences, Vol 51, Issue 3 M102-M107, Copyright © 1996 by The Gerontological Society of America
Event-related potential prolongation in Alzheimer's disease signifies frontal lobe impairment: evidence from SPECT imaging
D O'Mahony, J Coffey, J Murphy, N O'Hare, D Hamilton, M Rowan, P Freyne, JB Walsh and D Coakley
Mercer's Institute for Research on Ageing, St. James's hospital, Dublin.
BACKGROUND. The N2 and P3 components of auditory event-related potentials
(ERPs) and single-photon emission computed tomographic (SPECT) images are
separate independent biological markers of cerebral function and are
abnormal in Alzheimer's disease (AD). The relationship between ERP N2 and
P3 latencies and regional cerebral perfusion abnormalities in AD is
unknown. METHODS. ERP and SPECT data were obtained one week apart in 18
patients with "probable" AD of mild or moderate severity, and 12 healthy
age-matched elderly controls. Average premotor frontal, anterior temporal,
inferior parietal, and occipital cortical/cerebellar perfusion ratios were
calculated from the SPECT data and correlations with ERP N2 and P3
latencies derived for AD and control groups separately. RESULTS. ERP N2
latency was correlated significantly with the average frontal perfusion
ratio (r = -.59; p < .009), but correlations with average temporal,
parietal, and occipital ratios were nonsignificant in the AD group.
Similarly, ERP P3 latency was correlated significantly with the average
frontal perfusion ratio (r = -.65; p < .004), but not with the other
perfusion ratios in the AD group. In the control group, a partial
correlation between the average frontal perfusion ratio and the ERP N2
latency was noted (r = -.52; p < .09), but no other ERP/SPECT
correlations approached statistical significance. CONCLUSION. ERP N2 and P3
latency delay in AD is a function of differential frontal lobe
hypoperfusion.
