Acceptance and Commitment Therapy for Public Mental Health Promotion

As many people suffer from clinically relevant depression symptoms and consequently are at a high risk of actually developing a major depression, prevention interventions are crucial for reducing the onset thereof. In this thesis a new prevention intervention based on Acceptance and Commitment Therapy (ACT) and mindfulness, called “Living to the full”, for adults with mild to moderate depression was introduced. The “Living to the full” programme differs from the current indicated prevention by aiming the intervention on the promotion of positive mental health rather than primarily focusing on the reduction or prevention of mental illness. The programme is aimed at increasing the positive skills “psychological flexibility” and “mindfulness”. With these skills people learn to accept their unwanted thoughts and emotions, to be in contact with the present moment and to choose or persist in behaviour that is in line with important values and goals. The effectiveness of the “Living to the full” programme as both group course and as a self-help course with e-mail counseling were investigated in two randomized controlled trials with a waiting list as a control group. Medium to high effect sizes were found on depression and anxiety after the group and self-help course and at the three-month follow-up. Also “Living to the full” programme proved to effectively promote positive mental health, psychological flexibility and mindfulness. Furthermore, this thesis showed that by the improvement of psychological flexibility a reduction in psychological distress and improvement in positive mental health was established. Overall, this thesis concluded that the effectiveness of this programme is promising. The programme is already widely implemented in mental health care in the Netherlands. Evaluation of long term effects is now warranted.