Group intervention ‘Drop it!’ decreases repetitive negative thinking in major depressive disorder and/or generalized anxiety disorder : a randomised controlled study

Background Repetitive negative thinking (RNT) is considered to be an important transdiagnostic factor in the onset, course and recurrence of both depressive and anxiety disorders. This study aimed to investigate whether an add-on group intervention 'Drop it', compared to treatment as usual, would improve RNT, anxiety and depressive symptoms, as well as quality of life and self-esteem of patients with Major Depressive Disorder (MDD) and/or Generalized Anxiety Disorder (GAD). Methods Eighty patients were randomly allocated to 8 sessions of group intervention (n = 45) or a delayed treatment control group (n = 35). Both conditions continued their ongoing mental health care. Assessments took place before randomization, 12 weeks later (after group intervention) and at 3- and 9- months follow-up. Results Although all outcomes improved after the intervention, only the uncontrollability of rumination, worrying, distancing oneself from one's thoughts, and quality of life remained statistically significant after Bonferroni correction compared to the delayed treatment control group. Conclusions Group intervention improves RNT and quality of life of patients treated for MDD and/or GAD. Improvements remain stable until 9 months after treatment. Limitations of the study included the small sample size, the lack of a long-term follow-up in the delayed treatment control group and the inclusion of highly educated patients with mainly high comorbid generalized anxiety disorder and depression