Reliability of the Flash Visual Evoked Potential P2: Double-Stimulation Study.

The flash visual evoked potential P2 (FVEP-P2) has been identified as a potentially useful clinical, diagnostic tool for Alzheimer's dementia (AD) and mild cognitive impairment (MCIa) due to its association with cholinergic functioning in the brain. The FVEP-P2 is the second positive component of the VEP waveform elicited by a single strobe flash. Despite finding a selective delay in the latency of the FVEP-P2 in AD and MCIa groups, adequate levels of sensitivity and specificity have not been achieved due to natural group differences and inter-individual variability. In response, Fix and colleagues introduced a novel, double-stimulation paradigm that contained two strobe flashes (i.e., stimulations). The first stimulation served as a visual challenge while the second stimulation produced the recorded FVEP-P2 component. The results of that investigation indicated that the latency of the FVEP-P2 could be used to reliably discriminate between aMCI and healthy controls when the ISI of the double-stimulation condition was 100 ms or higher. Unfortunately, very little is known regarding the psychometric properties of the FVEP-P2 when produced by a double-stimulation condition. Consequently, we assessed the test-retest reliability of the FVEP-P2 latency produced by a single- and twelve double-stimulation conditions in a sample of young, healthy individuals (N = 20). Results indicated that while the FVEP-P2 latencies produced by the single- and double-stimulation paradigm were reliable, the intra-individual variability continued to be too high for the FVEP-P2 latency to be used clinically. Methods of reducing the intra-individual variability are discussed, including the use of monochromatic light.