Acceptance and commitment therapy as guided self-help for psychological distress and positive mental health: a randomized controlled trial

Background. In order to reduce the high prevalence of depression, early interventions for people at risk of depression are warranted. This study evaluated the effectiveness of an early guided self-help programme based on acceptance and commitment therapy (ACT) for reducing depressive symptomatology. Method. Participants with mild to moderate depressive symptomatology were recruited from the general population and randomized to the self-help programme with extensive email support (n = 125), the self-help programme with minimal email support (n = 125) or to a waiting list control group (n = 126). Participants completed measures before and after the intervention to assess depression, anxiety, fatigue, experiential avoidance, positive mental health and mindfulness. Participants in the experimental conditions also completed these measures at a 3-month follow-up. Results. In the experimental conditions significant reductions in depression, anxiety, fatigue, experiential avoidance and improvements in positive mental health and mindfulness were found, compared with the waiting list condition (effect sizes Cohen's d = 0.51-1.00). These effects were sustained at the 3-month follow-up. There were no significant differences between the experimental conditions on the outcome measures. Conclusions. The ACT-based self-help programme with minimal email support is effective for people with mild to moderate depressive symptomatology.