Event-related potentials in psychiatry: differentiating depression and dementia in the elderly.

Event-related potentials (ERPs) were recorded from 25 elderly patients and 26 normal controls to determine whether ERPs can aid in the differential diagnosis of depression and dementia. Two ERP measures were used: (1) P300 latency, and (2) N1 amplitude increase for a 14db tone intensity increase (i.e. intensity augmenting-reducing). While augmenting-reducing proved of little benefit, P300 latency was highly correlated with Mini-Mental State (MMS) scores and correctly identified 10 of 18 demented patients. None of the seven patients with psychiatric disorders (primarily depression) or 26 normals were misclassified. Better differentiation of depression and dementia resulted from combined use of P300 latency and MMS scores.