Changes in auditory P300 in patients with major depression and silent cerebral infarction

We examined event-related potentials in patients with senile depression and silent cerebral infarction (SCI) to clarify the features of the P300 component. P300 event-related potentials were recorded in drug-free depressed patients (N = 16) and normal controls (N = 17). All patients underwent magnetic resonance imaging and were classified as SCI-positive (N = 7) or SCI-negative (N = 9). In depressed patients, the P300 was reexamined after antidepressant treatment. Prior to treatment, P300 amplitudes in depressed patients were significantly smaller than those in normal controls (P < 0.01). P300 amplitudes increased significantly in SCI-negative patients following recovery (P < 0.05), but did not change in SCI-positive patients. SCI may interrupt the treatment-related P300 amplitude increase in depressed patients.