Plain English Summary
Background and study aims
The assessment and treatment of people with personality disorder is complicated by the variety of symptoms within individual disorders and high levels of overlap between disorders. A review of studies evaluating a range of psychological treatments for personality disorder showed encouraging results compared with standard care. Nevertheless, the strength of evidence was variable and the research focused predominantly on borderline personality disorder. This is despite the fact that only 1 in 10 are borderline personality disorder out of all the personality disorder diagnoses and interventions for this group are usually complex and of long duration. Thus, effective but less resource-intensive interventions (treatment) are required, not only for borderline participants but also for the broader range of participants with a personality disorder. Cognitive Analytic Therapy (CAT) talking therapy may meet this need. CAT intervention is a brief (limited to 16 24 sessions) that involves the patient actively in their treatment. It focuses on ways of managing distress and relationship difficulties that are common to all personality disorders. Despite CATs widespread adoption in the UK (www.acat.me.uk), the research supporting CAT remains limited to date. The present study was, therefore, designed to extend the evidence base.
Who can participate?
Adults who met the diagnostic criteria for a personality disorder and who had completed at least one previous episode of therapy.
What does the study involve?
Once referred, participants were assessed for eligibility to the study. Those who were eligible for the study and willing to participate were further assessed to find out their lifetime experiences of personality disorder symptoms. To this end, they attended a diagnostic interview and completed a series of questionnaires. Participants were randomly allocated into one of two groups, either CAT, or treatment as usual (TAU). The CAT group had 24 individual sessions with a therapist for 10 months. The TAU group received standard NHS care over the 10 months, typically comprising of general practitioner (GP) contact, care from the Community Mental Health Team and other clinical services. Both groups completed further questionnaires and attended another diagnostic interview at the end of 10 months, to assess the impact of their experiences. Participants in the TAU condition were offered CAT after this 10-month period. CAT participants completed some follow-up assessments18 months after treatment ended to re-assess their progress.
What are the possible benefits and risks of participating?
All participants will be offered a CAT therapy, which could reduce their personality disorder symptomology and improve their relationships. All participants were monitored throughout the study and had access to standard NHS care. The TAU participants were offered a 24-session CAT therapy after the study.
Where is the study run from?
The study took place in the Intensive Psychological Therapies Service, Poole: a Dorset HealthCare NHS Trust tertiary service for people with a personality disorder. Treatment as usual was also provided by Dorset HealthCare NHS Trust.
When is study starting and how long is it expected to run for?
The study commenced in 2001 and finished in 2010
Who is funding the study?
Dorset HealthCare NHS Trust
Who is the main contact?
Prof. Sue Clarke
Cognitive Analytic Therapy (CAT) for personality disorder: a randomised controlled trial comparing time-limited 24-session CAT versus treatment as usual
Twenty-four sessions of Cognitive Analytic Therapy (CAT) will lead to greater reductions in psychological symptoms and interpersonal difficulties for participants with a personality disorder, compared to Treatment as Usual (TAU).
South West, East Dorset Local Research Ethics Committee, 30 November 2000, ref: LREC 209/00/B
Single site single-blind randomised controlled trial with intention to treat analysis
Primary study design
Secondary study design
Randomised controlled trial
Patient information sheet
Not available in web format, please use the contact details below to request a patient information sheet
The intervention group received 24 sessions of Cognitive Analytic Therapy over 10 months as a treatment for Personality Disorder and were followed-up 18 months after the completion of the study.
The control group received treatment as usual, i.e. standard NHS care, over the 10 months of the study, and were offered CAT therapy following the 10-month assessment phase.
Primary outcome measure
Structured Clinical Interview for DSM-IV Axis II (SCID-II) to assess symptoms of personality disorder pre-therapy/TAU, post-therapy/TAU, and follow-up for the CAT condition only. To measure distress arising from interpersonal difficulties, we used a self-report questionnaire, The Inventory of Interpersonal Problems: 32-item (IIP). This was measured pre- and post- intervention for both groups, and at follow-up for the CAT group.
Secondary outcome measures
1. Adjustment, measured using the Clinical Outcomes in Routine Evaluation (CORE) self-report measure
2. Service satisfaction, measured using the Service Satisfaction Scale self-report questionnaire
3. Dissociation, measured using the Dissociative Questionnaire and the Dissociate Experiences Scale (DES) self-report questionnaires
4. Psychological problems and symptoms of psychopathology, measured by the Symptom Checklist-90-Revised self-report measure
5. Emotional Distress, measured by the Global Severity Index. All questionnaires were completed pre- and post-intervention, and at follow-up for the CAT group
6. Frequency and duration of all accident and emergency attendances and in-patient admissions, measured through access to the Dorset HealthCare NHS Trust Participant Administration System
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
1. Adult participants who met diagnostic criteria for a personality disorder
2. Participants who had completed at least one previous episode of therapy
Target number of participants
Participant exclusion criteria
1. Psychotic illness, substance dependence [as defined by Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV)] and intellectual disability
2. Participants who engaged in self-harming behaviour at least monthly were excluded, and referred for Dialectical Behaviour Therapy
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
St. Ann's Hospital
Dorset HealthCare University NHS Foundation Trust (UK)
11 Shelley Road
Dorset HealthCare NHS Trust (UK)
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
Not provided at time of registration
Intention to publish date
Participant level data
Not provided at time of registration
Basic results (scientific)
2013 results in http://www.ncbi.nlm.nih.gov/pubmed/23222038
Clarke S, Thomas P, James K, Cognitive analytic therapy for personality disorder: randomised controlled trial., Br J Psychiatry, 2013, 202, 129-134, doi: 10.1192/bjp.bp.112.108670.