Visual Evoked Potentials in Early Alzheimer's Dementia: An Exploratory Study

Abstract

Topographical maps of visual evoked potentials (VEPs) were recorded from 10 possible Alzheimer's disease (AD) patients and 10 control subjects. The purpose of the study was to determine if the two types of VEPs could function as a diagnostic screening for AD. Results of the statistical analysis did not reveal any latency differences between VEPs for the components elicited by either the pattern shift visual evoked potential (PSVEP)--or flash visual evoked potential (FVEP)--elicited components for AD patients compared with the control subjects; however, the information provided insight into results that are frequently lost with conventional evoked potential data. Statistically significant differences in amplitude were found between the P1 and the N2 of the PSVEP at 124, 126, and 130 ms, and at 116 ms for the FVEP.

Pattern Visual Evoked Potential (VEP) is Unaffected in the Early Stage of Mild Cognitive Impairment

“…However this is in contrast to Katz et al (1989) and Grayson et al (1995) who showed normal implicit times of the P100 in AD participants. Grayson et al (1995) did not detect latency differences using both the flash VEP and pattern reversal VEP.…”

“…However this is in contrast to Katz et al (1989) and Grayson et al (1995) who showed normal implicit times of the P100 in AD participants. Grayson et al (1995) did not detect latency differences using both the flash VEP and pattern reversal VEP. Their results were also supported by Iseri et al (2006) who also failed to show any significant differences in VEP P100 of their AD participants relative to control.…”

Effects of flash mode and intensity on P2 component latency and amplitude

“…Although the selective P2 delay is a robust finding across laboratories and techniques, some studies (e.g., Grayson et al, 1995;Haupt et al, 1994;O'Mahony et al, 1993;Sloan et al, 1994) have not replicated the generally reported differences between groups of AD patients and controls. The source of the problem is unclear, but may stem in part from clinical diagnostic inaccuracies (e.g., Grayson et al, 1995) or differences in recording site selection (e.g., Haupt et al, 1994), flash mode (e.g., Sloan et al, 1994), or the intensity (e.g., O'Mahony et al, 1993) of the flash used to evoke the VEP.…”

“…The source of the problem is unclear, but may stem in part from clinical diagnostic inaccuracies (e.g., Grayson et al, 1995) or differences in recording site selection (e.g., Haupt et al, 1994), flash mode (e.g., Sloan et al, 1994), or the intensity (e.g., O'Mahony et al, 1993) of the flash used to evoke the VEP.…”

“…Studies relying on looser diagnostic criteria such as bpossibleQ AD (e.g., Grayson et al, 1995) are virtually guaranteed to yield ambiguous findings. Similar problems plague the selection of healthy control participants.…”