Dose-Effect Relations for Psychotherapy of Mild Depression: A Quasi-Experimental Comparison of Effects of 2, 8, and 16 Sessions

Clients (N = 105) presenting with mild depression were assigned to receive 2, 8, or 16 sessions of psychotherapy in a quasi-experimental design involving 2 clinical trials. Rates of recovery were estimated as the proportion of each group achieving reliable and clinically significant change at the end of treatment (shortly after the prescribed dose had been administered) and at a follow-up assessment 2 to 3 months later. Results supported the hypothesis that recovery from interpersonal problems typically requires higher doses of psychotherapy than does recovery from symptoms of depression or broader distress.