Plain English Summary
Background and study aims
Mental disorders are impairing for the individual and are associated with low quality of life and reduced well-being. Treatment resistance (inadequate response to treatment) occurs in 25%-50% of patients. Acceptance and Commitment Therapy (ACT), a further development of traditional behavioral therapy, may offer a starting point for treatment-resistant patients precisely because the therapy does not attempt to eliminate symptoms. Instead, the therapy helps the patient to stop the unsuccessful struggle by fostering the willingness to openly experience emotions and thoughts as such. ACT has shown promising results even with highly impacted patients suffering from diverse psychological disorders. What remains unknown is whether and to what extent ACT transfers to treatment-resistant, chronic (long-term) patients treated in routine in- and out-patients treatment settings. Furthermore, the mechanisms underlying treatment success or failure remain largely unknown. This study will therefore examine the effectiveness of ACT treatment for patients with treatment-resistant disorders.
Who can participate?
Inpatients and outpatients aged 18 – 65 presenting for specialized treatment in a psychiatric university clinic
What does the study involve?
Both the inpatient unit and outpatient units of the Universitären Psychiatrischen Kliniken in Basel both apply Acceptance and Commitment Therapy. The treatment program in the inpatient unit involves intensive psychotherapy, individually and in groups. Treatment in the outpatient unit consists of individual intensive psychotherapy. The goal is to limit treatment to 3 months on average, however the length differs by individual, and is determined by clinical necessity. In addition, the patients are followed-up once they leave the clinic after 1, 4, 9 and 12 months.
What are the possible benefits and risks of participating?
Participants can obtain a summary of their responses that will be shared with their treatment provider. The results will inform us about the processes involved in successful and unsuccessful treatment. Participation in the assessment procedures of this study is not known to be associated with any risks.
Where is the study run from?
Universitäre Psychiatrische Kliniken Basel (Switzerland)
When is the study starting and how long is it expected to run for?
May 2016 to February 2021
Who is funding the study?
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (Switzerland)
Who is the main contact?
Prof. Andrew Gloster
Effectiveness of Acceptance and Commitment Therapy (ACT)-based therapy
1. The Acceptance and Commitment Therapy (ACT)-specific intervention will lead to significant positive changes in two treatment settings (i.e., inpatient and outpatient).
2. Psychological flexibility will moderate the negative impact of stressors such that it will be buffered in patients who show high levels in psychological flexibility.
Long-Term Course and Outcome:
3. Positive changes observed between pretest and post-test will remain stable for 12 months following treatment in the ACT-condition.
4. The percentage of patients who successfully apply treatment processes following treatment will differ between the in- and out-patient settings. However, irrespective of setting, those patients who apply the processes will have less relapse.
Ethikkommission Nordwest- und Zentralschweiz, May 2016; Ref: EKNZ: 165/13
Effectiveness study with two non-randomized treatment arms (i.e., inpatient and outpatient) consisting of self-referring patients
Primary study design
Secondary study design
Non randomised study
Patient information sheet
Not available in web format, please use contact details to request a participant information sheet
Transdiagnostic, treatment-resistant patients, presenting for specialized in- and out-patient treatment
Both the inpatient unit and outpatient units of the Universitären Psychiatrischen Kliniken in Basel will both apply Acceptance and Commitment Therapy. The treatment program in the inpatient unit involves intensive psychotherapy, individually and in groups. Treatment in the outpatient unit consists of individual intensive psychotherapy. Patients self-present for treatment and there is no randomisation. The goal is to limit treatment to 3 months on average, however the length differs by individual, and will be determined by clinical necessity, and cannot be guaranteed a priori.
The study includes a pre-, post- and follow-up measurement. The follow up (FU) assessments will take place after 1, 4, 9 and 12 months.
Primary outcome measure
1. Symptoms: Brief Symptom Checklist (BSCL)
2. General Functioning: World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0; 12-item version)
3. Well-Being: Mental Health Continuum (MHC-SF)
Primary outcomes are measured at baseline, post, and 12 months follow up.
Secondary outcome measures
1. Psychological flexibility/emotional avoidance
5. Obsessions and compulsions
6. Social Interaction
7. Social fear
8. Process of psychological flexibility
9. Committed action
10. Cognitive fusion
13. Meaning of life
14. (Problematic) emotion regulation
15. Overall social support
16. Relationship satisfaction
17. Social network quality
19. Perceived stress
20. Daily stress
21. Prosocial behaviors
Secondary outcomes are measured at baseline, post and 12 months follow up. Process measures of psychological flexibility, social interactions, social network quality, and daily stress are additionally measured at 1, 4 and 9 month follow-up.
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
1. Individuals 18 – 65 years of age
2. Inpatients and outpatients presenting for specialized treatment in a psychiatric university clinic
3. A history of at least one course of previous therapy
4. Signed letter of consent
Some patients without previous therapy experience were included to enable full modelling of patients from those without treatment experience to those with treatment experience.
Target number of participants
Participant exclusion criteria
1. Less than 18, greater than 65 years of age
2. Inability to understand the local language (German) in written form
3. Inability to complete the study design
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Universitäre Psychiatrische Kliniken Basel
University of Basel (Switzerland)
c/o Prof. Dr Andrew Gloster
Department of Psychology
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
Swiss National Science Foundation, Fonds National Suisse de la Recherche Scientifique, Fondo Nazionale Svizzero per la Ricerca Scientifica, Fonds National Suisse, Fondo Nazionale Svizzero, Schweizerischer Nationalfonds, SNF, SNSF, FNS
Funding Body Type
private sector organisation
Funding Body Subtype
Trusts, charities, foundations (both public and private)
Results and Publications
Publication and dissemination plan
To be confirmed at a later date
Intention to publish date
Participant level data
Available on request
Basic results (scientific)
2019 protocol in: https://www.ncbi.nlm.nih.gov/pubmed/31182051 (added 12/06/2019)