Effects of treatment duration and severity of depression on the effectiveness of cognitive-behavioral and psychodynamic-interpersonal psychotherapy.

TLDR

A randomized study of 117 depressed clients, stratified by severity, assigned to 8 or 16 manualized sessions of CBT or PI, with five clinicians delivering all four conditions. CBT and PI produced comparable improvements across most outcomes, with CBT showing a modest benefit on the Beck Depression Inventory, and neither treatment’s speed nor overall advantage differed by session length except that patients with severe depression benefited more from 16 than 8 sessions.

Abstract

A total of 117 depressed clients, stratified for severity, completed 8 or 16 sessions of manualized treatment, either cognitive-behavioral psychotherapy (CB) or psychodynamic-interpersonal psychotherapy (PI). Each of 5 clinician-investigators treated clients in all 4 treatment conditions. On most measures, CB and PI were equally effective, irrespective of the severity of depression or the duration of treatment. However, there was evidence of some advantage to CB on the Beck Depression Inventory (Beck, Ward, Mendelson, Mock, & Erbaugh, 1961). There was no evidence that CB's effects were more rapid than those of PI, nor did the effects of each treatment method vary according to the severity of depression. There was no overall advantage to 16-session treatment over 8-session treatment. However, those presenting with relatively severe depression improved substantially more after 16 than after 8 sessions.