Auditory event related potentials in major depression: prolonged P300 latency and increased P200 amplitude.

BACKGROUND: Some studies have shown disturbances in auditory event related potentials (AERPs) in patients with major depression.
METHODS: In this exploratory study, the late AERP components, N100 (latency), P200 (amplitude and latency) and P300 (amplitude and latency) were recorded in 68 subjects, i.e. 39 major depressed subjects, with (n=4) or without (n=35) cognitive deterioration, 18 patients with Alzheimer's dementia (SDAT) and 11 normal volunteers. Twenty-five major depressed patients had repeated measurements of AERPs both before and after treatment with antidepressants.
RESULTS: Major depressed subjects without cognitive deterioration had significantly higher P300 latency and P200 amplitude than normal volunteers. SDAT patients and major depressed patients with cognitive impairment had a significantly higher P300 latency than depressed patients without cognitive impairment. In the latter, no significant alterations in any of the AERP components upon subchronic treatment with antidepressants were recorded. Nonresponders to antidepressant therapy had significantly higher pretreatment P300 latency and P200 amplitude than responders to treatment (P=0.006) and normal volunteers (P=0.0004).
CONCLUSIONS: The findings may suggest that delayed P300 latency as well as increased P200 amplitude accompany major depression and may predict a nonresponse to subsequent antidepressive therapy.