Psychological decentering for the prevention of depression and the promotion of wellbeing in adolescents: A randomised controlled efficacy trial

Background. Depression and anxiety typically begin during adolescence and are among the most common mental health problems. Helpful psychological treatments exist but the benefits are limited. One-in-three patients do not improve during treatment, and one-in-three who improve may experience symptom relapse. Many individuals therefore experience complex, long-term needs that increase pressure on already stretched health services. Intervening early to prevent depression and anxiety is preferable. However, no early-stage intervention programs for adolescents have full clinical research support. We propose to investigate the efficacy of a low-cost, low-intensity, online early-stage psychological intervention for adolescent depression and anxiety. It works by teaching, via short daily online sessions, a core psychotherapeutic skill critical for the effective management and regulation of everyday emotional distress — psychological decentering. Psychological decentering refers to the ability to psychologically step back and separate oneself from one s mental experiences to process them from a different, more objective, perspective. To evaluate the feasibility of our adolescent psychological decentering (DECADES) training we carried out a randomised controlled feasibility trial (RCT). Compared to adolescents in an active control group, the DECADES group reported significant improvements in their ability to use psychological decentering as well as significant increases in well-being and decreases in depression severity (with medium effect sizes; Cohen s ds=0.57–0.67). The feasibility data indicated good recruitment, engagement, adherence, and acceptability of the programme. Research Aims: Our primary aim now is to (1) determine the efficacy of DECADES training in reducing depression symptoms and improvements in wellbeing in a targeted community-sample of at-risk adolescents. Other aims are to (2) identify mechanisms-of-change that drive clinical outcomes and (3) explore the health-economic benefits of DECADES training. Plan of Investigation: We propose a two-arm randomised controlled efficacy trial comparing DECADES training with an active control condition (combining physical exercise with cognitive training). Our co-primary outcomes are depression severity based on the Centre for Epidemiological Studies Depression Scale and wellbeing on the Warwick-Edinburgh Mental Wellbeing Scale (13). Secondary outcomes include measures of anxiety and socio-emotional difficulties. We plan three datapoints – baseline, post-intervention and a four-month follow-up. Participants are school-based adolescents (16-19 years) with heightened depression symptoms. N=552 participants will be recruited; 276 per arm. This provides 80% power to detect medium-effect-sized changes in symptom severity from baseline to four-month follow-up. PPI and equity. We have, and will continue to, work with a panel of PPI advisors. Our research on psychological decentering has been co-developed with PPI contributors (aged 16-20 years) from the initial phases of construct validity, theory testing, and feasibility/piloting. For the proposed trial, our PPI Co-Applicant will coordinate a further review of our trial materials following adaptions from our feasibility stage. They will also provide guidance on an inclusive recruitment campaign that promotes findings that are generalisable to large community-based groups of young people including under-served groups. Outputs: The principal anticipated output is an efficacious psychological intervention for preventing depression and enhancing wellbeing in adolescents. This output would provide a robust platform for a scaled up, multi-centre definitive effectiveness trial of the DECADES programme.