P300 AMPLITUDE IN NON-BIPOLAR, MELANCHOLIC DEPRESSION

P300 event related potential (ERP) was recorded using the auditory 'od dball' paradigm in 17 melancholic, drug-free depressive patients and 2 2 normal controls. Repeat ERP recordings were obtained from 13 patient s after recovery with ECT. Pretreatment P300 latencies were not differ ent between patients and controls, nor did they change in the depressi ves following recovery. Pretreatment P300 amplitudes in depressives we re smaller (P < 0.02) than in controls and negatively correlated with severity (P < 0.05). P300 amplitudes significantly increased in patien ts following recovery (P < 0.05) and normalized. P300 may be a state m arker for melancholic depression.