Use the drop-downs below to read the updates for each of the different workstreams of the PETAL programme.


Workstream 1 

Rapid Realist Review 

The review has been published in the journal PLOS One (see dissemination page for access to the paper). We recruited a local reference group of learning disability healthcare professionals and experts to help us complete the review and provide essential feedback. To test the programme theories, we interviewed healthcare professionals and services managers in the NHS, along with family and paid carers who work with people with learning disabilities who display aggressive challenging behaviour. This work has been completed and the results have been written up and published. An accessible summary of the paper has also been published as an NIHR alert. Click here to read.

Qualitative Study

We interviewed 42 people with learning disabilities who were recruited from 7 sites across England, Scotland and Northern Ireland. We analysed the themes that came up during the interviews with family and paid carers, healthcare professionals working in the NHS and adults with learning disabilities. The interviews explored the barriers and facilitators that are associated with treatment outcomes in adults with learning disabilities who display aggressive challenging behaviour. We have published this work in in NIHR Open Research (see dissemination page for access to the paper). 

Workstream 2

Clinical Record Interactive Search (CRIS)

We explored a mental health database called CRIS (Clinical Record Interactive Search) to identify people who are most likely to come in contact with crisis services due to aggressive challenging behaviours or mood dysregulation. The results of this workstream have been published in the journal European Psychiatry (see dissemination page for access to the paper). 

Workstream 3

PETAL therapy development

We held 7 co-production meetings to design the PETAL therapy. We have developed and finalised the PETAL therapy manual, participant and carer workbooks and the therapist training programme. These were co-designed with experts by experience and were also informed by the findings from Workstreams 1 and 2.

Workstream 4 

The PETAL Trial 

We have received ethics approval for the PETAL trial. We began the feasibility trial in February 2023. We have now reached the end of the feasibility phase. 

The main trial started in January 2024. We have 6 sites which are currently open to recruitement. More sites will be opening soon. Some sites have already recruited participants.

General Updates

Public and Patient Involvement

We have held 11 service user meetings and 11 family and carer advisory group meetings. There have also been 3 combined meetings with members from both groups. Both groups have commented on the content of papers written up for publication and have been heavily involved with the development of the PETAL therapy.


We have held 9 meetings with the implementation committee to discuss barriers that may arise in implementing the PETAL therapy into NHS services and to develop strategies to overcome this.

Minimally Clinically Important Difference

We completed a piece of research to determine the smallest important change in people with learning disabilities for the measure called Aberrant Behaviour Checklist – Irritability (ABC-I). This helped us understand what is the smallest change in people’s health and well-being that indicates whether a treatment produced benefits for the individual. Visit the Dissemination tab to access the publication.