Prevention of anxiety disorders and depression by targeting excessive worry and rumination in adolescents and young adults: A randomized controlled trial.

BACKGROUND: This randomized controlled trial evaluated the efficacy of a preventive intervention for anxiety disorders and depression by targeting excessive levels of repetitive negative thinking (RNT; worry and rumination) in adolescents and young adults. METHODS: Participants (N = 251, 83.7% female) showing elevated levels of RNT were randomly allocated to a 6-week cognitive-behavioral training delivered in a group, via the internet, or to a waitlist control condition. Self-report measures were collected at pre-intervention, post-intervention, 3 m and 12 m follow-up. RESULTS: Both versions of the preventive intervention significantly reduced RNT (d = 0.53 to 0.89), and symptom levels of anxiety and depression (d = 0.36 to 0.72). Effects were maintained until 12 m follow-up. The interventions resulted in a significantly lower 12 m prevalence rate of depression (group intervention: 15.3%, internet intervention: 14.7%) and generalized anxiety disorder (group intervention: 18.0%, internet intervention: 16.0%), compared to the waitlist (32.4% and 42.2%, respectively). Mediation analyses demonstrated that reductions in RNT mediated the effect of the interventions on the prevalence of depression and generalized anxiety disorder. CONCLUSIONS: Results provide evidence for the efficacy of this preventive intervention targeting RNT and support a selective prevention approach that specifically targets a known risk factor to prevent multiple disorders.