Long-Term Effects of Positive Psychotherapy Compared to Cognitive Behavior Therapy in Clinical Depression: An 18 Month Follow-Up Randomized Controlled Trial

Background/Objectives: Positive Psychotherapy (PPT) is an empirically supported treatment that directly targets positive resources and personal strengths as its primary logic. PPT is effective in amplifying happiness and well-being as an additional way to enhance positive mental health while also in ameliorating symptoms of negative affect, especially in depression, anxiety disorders and stress disorders. However, only few studies have been conducted to investigate these effects in the long run. Methods: This study examined the long-term outcomes of PPT in comparison to an active control treatment, Cognitive Behavioral Therapy (CBT). Forty-nine out-patient participants with a DSM-IV diagnosis for depressive disorder (MDD, Dysthymia) were treated with 14 sessions of manualized PPT (n = 23) or CBT (n = 26) group therapy. In a randomized controlled 2-center-study, questionnaires on depressive symptoms (BDI-II, MADRS, DHS), psychological distress (BSI), and well-being related outcomes (FS, PPTI, SWLS) were administered at baseline and 18 months follow-up. Results: Analyses using linear mixed models indicated significant differences in long-term treatment outcome for depressive symptoms (BDI-II, DHS, MADRS) and satisfaction with life (SWLS) depicting better outcomes for the PPT group. Between group effect sizes at 18 months follow-up were primarily in the middle range for all outcome measures, in favor of PPT. Conclusions: This study provides support for the long-term efficacy of PPT in the treatment of depression and improvement of positive resources.