CLINICAL-APPLICATION OF ELECTROPHYSIOLOGICAL MARKERS IN THE DIFFERENTIAL-DIAGNOSIS OF DEPRESSION AND VERY MILD ALZHEIMERS-DISEASE

Background-Current evidence indicates that, on their own, neither flas h visual evoked responses (FVEPs) nor event related potentials (ERPs) are sufficiently useful to the clinician in the very early stages of m emory dysfunction. However, the possibilities for the combined use of these measures has not been fully explored. Methods-This study examine d the clinical utility of combined FVEP and ERP-P300 component latenci es as predictive markers in 16 patients with Alzheimer's disease, 15 p atients with depression, and 21 control subjects. Results-There were s ignificant group differences in FVEP P2 latency (P = 0.004) between th e controls and both the depressive patients and those with very mild A lzheimer's disease. were no statistically significant differences for the ERP component (N2/P300) amplitudes or latencies. The P300 componen t latency was positively correlated with both the FVEP N2 and FVEP P2 component latencies in the patients with Alzheimer's disease but not i n the control subjects or the depressed patients. A discriminant funct ion, using two ERP and two FVEP component measures, gave an overall co rrect classification rate for dementia of 78%. In this study of very m ildly impaired patients the FVEP latencies provided a more sensitive m arker for the presence of cognitive dysfunction than P300 latency dela y. Conclusions-The findings support the use of multimodal evoked poten tials in the differential diagnosis of very mild Alzheimer's disease a nd normal aging.