Is there a delay in the onset of the antidepressant effect of electroconvulsive therapy?

The severity of depression in 11 drug-free unipolar patients diagnosed with definite major depressive disorder was assessed using the Hamilton Rating Scale for Depression during a course (5-10 treatments) of bilateral electroconvulsive therapy (ECT). The degree of improvement after three treatments of ECT was six times greater than the improvement that occurred over the remainder of the course. Although depressed patients who recover with ECT require repeated treatments, the treatments early in a course of ECT can have marked antidepressant effect.