"Normal' P300 amplitude predicts rapid response to ECT in melancholia.

Consenting melancholic depressives (n = 17) were treated with bilateral ECT under anaesthesia. All patients except two were antidepressant-naive. The auditory P300 event-related potential (ERP) was recorded before and after the ECT course. The latency of P300 in depressives before treatment did not differ from controls, but the amplitude was smaller than in matched controls (n = 15). The P300 amplitude was larger in depressives who had rapid response than in the rest. Rapid responders did not differ from controls on P300 amplitude before treatment. Hence it is suggested that "Normal' P300 predicts rapid therapeutic response to ECT in melancholia.