Cortical evoked potentials and clinical rating scales as measures of depressive illness.

Relationships between clinical ratings and cortical evoked potentials were examined before and during antidepressant drug treatment in 32 patients with major depressive disorder (DSM-III). Clinical rating scales included Hamilton Rating Scale for Depression, Beck Depression Inventory, Present State Examination (PSE) and Newcastle Scale. Evoked potentials included contingent negative variation (CNV), post-imperative negative variation (PINV) and auditory evoked potential (AEP) There were close correlations between all rating scales, and factor analysis produced only one component, suggesting that the common variance between them related to severity of depression. CNV magnitude before treatment correlated negatively with severity of depression regardless of diagnostic category. Depressed patients had a prominent PINV which persisted during antidepressant treatment. The amplitude of late components (N1P2) of the AEP was reduced strikingly in patients with a history of suicide attempts.