Classification of depression and response to antidepressive therapies

Two hundred inpatients suffering from primary depressive illness were studied. Seventy eight of the patients were treated by electroconvulsive therapy (ECT) and 122 patients received antidepressant medication. Response to ECT and antidepressant medication at 4 weeks showed a curvilinear relationship to Newcastle scores. Patients with Newcastle scores in the middle range (4-8) showed significantly higher percentage improvement than those with low (0-3) and high (9-12) scores. Ninety five patients with unipolar depression who received lithium therapy for one year were also studied. Response to lithium showed a linear relationship to Newcastle scores in these patients. It is suggested that these differences in response to antidepressant therapies reflect the heterogeneity of depressive illness.