What happens after five years?: The long-term effects of a four-session Acceptance and Commitment Therapy delivered by student therapists for depressive symptoms

Brief interventions can be viable treatment options worth consideration in addressing the growing need for treatments of subclinical and clinical depressive symptoms. However, there is uncertainty regarding the long-term benefits of these interventions. The aim was to examine the long-term (5-year) effects of a 4-session Acceptance and Commitment Therapy (ACT) intervention for low mood delivered by novice therapists in order to see whether lasting effects could be achieved cost-effectively with four intervention sessions. Originally, 57 self-referred clients were randomized into two groups: an intervention group and a waiting-list control group which received treatment later. The groups were combined both at the 6-month (n=48) and the 5-year (n=35) follow-up measurements to examine intervention effects. The results indicate a good effect size for depressive symptoms (the Beck Depression Inventory (BDI)): d=1.45 (CI 1.10-1.80) through the five-year study period. All in all, approximately 40% of the participants reported minimal to no depressive symptoms based on the primary outcome measure, the BDI (scores 0-9), both at post- and 5-year follow-up measurements.