Is there a dose-effect relationship between the number of psychotherapy sessions and improvement of social functioning?

Objectives and design This study describes a randomized controlled trial which aimed to evaluate whether 16 sessions of psychotherapy combined with pharmacotherapy is more effective in relieving depression and improving social functioning than 8 sessions of psychotherapy combined with pharmacotherapy. Methods. Randomized controlled trial comparing two treatment conditions with different psychotherapy dosages in out-patients with major depression. All patients studied had a baseline score of at least 14 points on the 17-item Hamilton Depression Rating Scale (HDRS). The two conditions consisted of 8- or 16-session short psychodynamic supportive psychotherapy, both in combination with pharmacotherapy. Efficacy was assessed using the 17-item HDRS, the clinical global impression of severity and of improvement, the depression subscale of the Ninety Symptom Checklist, the Quality of Life Depression Scale, and the Groningen Social Disability Schedule. Results. Social functioning improved significantly in both groups. No significant differences were found between 8 and 16 sessions with regard to social functioning. A significant advantage is found for patients in remission on 5 of the 11 dimensions in social functioning over patients not in remission. Conclusions. At the end of treatment, no clear differences are found between 8 or 16 sessions of psychotherapy - both combined with pharmacotherapy - with regard to severity of depression and social functioning. It is thus still unknown if patients with major depression show more improvement in social functioning and less symptoms of depression after 16 sessions of combined therapy than after 8 sessions. Currently, it seems that for major depression 8 sessions of combined therapy are equally effective as 16 sessions. © 2010 The British Psychological Society