ACT treatment for youth : a contextual behavioral approach

Sammanfattning: Background: Mental and substance abuse disorders in children and youth are the leading cause of disability in the world. According to the World Health Organization (2018), approximately 20% of the world’s children and adolescents suffer from mental health disorders or problems. Mental health problems among youth have increased between 1950 and 2016, and Sweden stands out, with a marked increase in internalizing mental health symptoms, even when compared to other Scandinavian countries. Increases are as sharp for both boys and girls, but girls report more problems. The most common problems include symptoms of anxiety, depression, and stress, and they often come together. To address those problems, we need to intervene on a societal level as well as helping youth directly. We can and should help at different levels and stages of these problems; helping youth at early stages can spare them a lot of suffering. To scale up the availability of treatments, we need to transfer some treatment delivery from highly specialized staff to less-specialized staff. We also need to understand what causes mental health problems and how effective treatments work. To this end, acceptance and commitment therapy (ACT) is promising, along with the construct of psychological flexibility (PF). There is initial support for using ACT for youth mental health problems; however, more research is needed. Aims: The overall aim of this thesis was to test and develop transdiagnostic group treatments for different youth populations. We wanted to test the interventions under real-world conditions when delivered by less-specialized staff. And to begin understanding possible mechanisms of change, we did the first replication on youth of the psychometric properties of the instrument Avoidance and Fusion Questionnaire for Youth (AFQ-Y) for detecting the PF construct. We also wanted to explore whether PF mediated the outcomes in one of the studies. The specific aims were as follows: Study I: Test the effectiveness of a brief transdiagnostic ACT group intervention in helping youth with subthreshold symptoms of stress and depression, and test it under real-world conditions in schools when delivered by less-specialized staff. Study II: Test the psychometric properties of the instrument AFQ-Y, see how it works in Swedish, and check the validity and reliability of the shorter form of the instrument (AFQY8). Study III: Test the effectiveness and feasibility of a brief transdiagnostic ACT group intervention for youth with comorbid problems in residential care. We also wanted to see whether increased PF mediated potential positive outcomes, and to test it under real-world conditions in residential care when delivered by less-specialized staff. Methods: In Study I we screened 247 youth (ages 14 through 15) in a Swedish public high school. Students with stress and mental health problems were invited to participate. Thirtytwo youth were randomized to either get the ACT intervention or be referred to individual support from the school nurse (treatment as usual, or TAU). In Australia we included 66 youth (12 through 18 years) with mild to moderate depressive symptoms from five schools and randomized them to ACT or TAU. In Study II we used data collected in the study described in Paper III to assess the psychometric properties of AFQ-Y17 and AFQ-Y8. In Study III we included 160 adolescents (ages 15 through 20) with psychosocial problems who had been mandated to inpatient residential care. Ninety-one youth at five sites received the addition of a 12-hour ACT group intervention on top of treatment as usual (TAU+ACT), and the remaining 69 youth at three matched sites received only TAU. The ACT intervention was delivered by regular ward staff without formal psychotherapeutic training. We measured participants at five time points over an 18-month period. Results: In Study I, results demonstrated that ACT in group format reduced the primary outcomes of youth stress and depression, with large effect sizes compared to the control group. In the Australian study, youth increased their PF with a large effect size. In the Swedish study, we observed marginally significant decreases of anxiety and increased mindfulness skills, with large and medium effect sizes, respectively. Participants in both Sweden and Australia reported liking the ACT intervention. In Study II, both the AFQ-Y17 and AFQ-Y8 demonstrated adequate psychometric properties. In Study III, the addition of ACT in group format reduced the primary outcomes of youth depression and anxiety, with small effect sizes compared to TAU alone at post-treatment. Effects were not significant at 18-month follow-up but continued to favor ACT, with small effect sizes. At post-treatment, increased PF mediated the reductions in anxiety. On the secondary outcomes of hyperactivity, peer problems, and better psychosocial functioning at large, effects in favor of ACT were found, all with small effect sizes. The improvements with fewer peer problems and better psychosocial functioning were observed in both youth selfreports and reports from treatment staff at the treatment unit. Conclusions: ACT as a short transdiagnostic group treatment is effective in reducing youth stress, symptoms of depression, and possibly anxiety when tested under real-world conditions in schools and when delivered by less-specialized staff. Adding a short transdiagnostic ACT group treatment on top of TAU for youth with comorbid problems in residential care is one way to reduce symptoms of depression and anxiety and other problems, such as fewer peer problems, reduced hyperactivity, and better overall psychosocial functioning. Increased PF mediated the reduction in anxiety. The AFQ-Y8 is a reliable, valid, and brief instrument for measuring PF among youth, with broad clinical and research utility.