[The psychological flexibility model: a new approach to mental health]

This paper presents a vision of mental health using the model of psychological flexibility of Acceptance and Commitment Therapy (ACT). ACT is a representative approach of the third wave of cognitive-behavioural therapy (CBT). This article first describes the theoretical and practical aspects of ACT and, in a second part, reviews some of the empirical data supporting its clinical use. Due to the high rate of comorbidity in mental health settings, transdiagnostic approaches in CBT, such as ACT, have recently become popular and particularly appealing to various clinical settings.

The theoretical aspects underlying ACT, as well as its clinical components in the treatment of psychopathology were described based on major books in this area, such as Hayes, Strosahl and Wilson (2012). A descriptive literature review was undertaken to explore the data on the efficacy of ACT for the treatment of mental health problems. Psycinfo and Medline, as well as the Association for Contextual Science website were analyzed for relevant articles. The key search terms were: "Acceptance and Commitment therapy" or "ACT" or "acceptance" or "mindfulness" or "defusion." The reference lists of the articles retrieved were also analyzed. The articles that were not in English or French were excluded.

Data suggest that ACT is particularly effective for stress, anxiety disorders, depression, substance abuse and various chronic medical conditions. The six processes of the model of psychological flexibility have been validated based on the results of correlational and meditational studies. More than seventy randomized clinical trials and a meta-analysis including 18 randomized control trials conclude that ACT is more effective than waiting list, placebo and treatment as usual control conditions.

ACT is a promising and evidence-based approach in mental health for the treatment of anxiety and depression as well as for complex and chronic conditions. More research is needed to further validate its theoretical model and further refine our understanding of how ACT could be effective for the management of mental health illness and how it could enhance quality of life for people who suffer from these conditions.