IASSIDD 2021 Amsterdam - Annemieke Hoogstad

Annemieke Hoogstad presents her research project at the IASSIDD congress Amsterdam: Assessment and treatment of Post Traumatic Stress Disorder in people with a severe to moderate intellectual disability.

After working as a psychologist and trauma-therapist for years, Annemieke Hoogstad started this research-project in 2020 in collaboration with dr. Liesbeth Mevissen working for her own practice and Trajectum, and prof. dr. Robert Didden connected to the Radboud University and Trajectum.

Contact Annemieke Hoogstad at a.hoogstad@amerpoort.nl


​In this project, our aim is to gain insight in how Post Traumatic Stress Disorder (PTSD) is manifested and how it can be diagnosed and treated in adults with a severe to moderate intellectual disability (ID).

Research method

The research project will be executed between June 2020 and June 2025 and for now contains four research components, each component focusing on one specific theme. These specific themes are explained below.

Target group

The research will be conducted at adults (18+) with a severe to moderate intellectual disability receiving residential care from Amerpoort, Sherpa or ASVZ.

Research topic

People with an ID have a greater risk of developing PTSD. As research mainly focusses on people with mild to borderline ID, very little is known regarding diagnosis and treatment of PTSD in people with more severe levels of ID: people with an IQ <50 and a developmental age <6 years. They are verbally limited and to a large extent dependent on the care of others, also for their psychological well-being.

Recognizing and interpreting PTSD symptoms in people with severe to moderate ID pose challenges because PTSD symptoms may be seen as isolated challenging behaviours in people with an ID, while anger management issues, self-destructive behaviour and aggression can also be symptoms of PTSD. There is currently no valid and reliable diagnostic tool for identifying PTSD in this target group. And even when PTSD symptoms are being recognised, it remains unclear which treatment is appropriate. More knowledge about diagnostics and effective interventions is needed.

Our study focusses on both diagnostics and interventions and will consist of four components: Firstly adaptation of an existing trauma interview, secondly a pilot to evaluate a trauma interview for adults with a severe to moderate ID, thirdly a pilot exploring the effects of Eye Movement Desensitization and Reprocessing therapy on adults with a severe ID and finally adaptation of the trauma-interview based on the pilot-results and subsequently investigating the psychometric qualities in a larger sample. The two pilots are made possible by the Dutch EMDR association (VEN).


Part 1: development of the DITS-ID- SMo-version

Research period 2020-2021

We adapted the existing Diagnostic Interview for Trauma Stressors in people with a Mild Intellectual Disability (DITS-ID) (Mevissen, Didden & De Jongh, 2018), resulting in a DITS-ID version for severe to moderate ID (DITS-ID-SMo-version) (Mevissen, Hoogstad, De Jongh & Didden, 2021). We chose to adapt this interview, because it includes both the DSM-5 criteria for PTSD in adults and those for children under 6. The DITS-ID asks for DSM-5 traumatic events and other adverse life events and PTSD symptoms. The DITS-ID also measures the daily interference by means of a thermometer score.

The adaptations were based on literature, expert experiences, and the clinical experiences of the research team. Literature was consulted about life events and characteristics of people with a severe to moderate ID, about PTSD in children with a similar developmental age, and PTSD questionnaires for children younger than 6. We used a separate questionnaire for each item of the DITS-ID to ask the experts whether in their experience the life event or symptom in question occurred in people with a severe to moderate ID.

Part 2: Pilot DITS-ID

Research period 2021-2022

In our first pilot, we will interview direct caregivers and relatives (mostly parents) of 25 adults with a severe to moderate ID. We will investigate three topics. Firstly, the psychometric qualities of the severe to moderate ID-version of the DITS-ID will be investigated. To investigate the interrater reliability all DITS interviews are conducted by a trained psychologist/master’s student, videotaped and scored by a second evaluator. To establish the convergent validity the Aberrant Behaviour Checklist is conducted. To ensure content validity, a trauma screen for young children between 3 and 6 years is conducted based on the Child and Adolescent Trauma Screen 3-6 years. Secondly, descriptive analyses are conducted to describe the exposure to adverse life events and the manifestation of PTSD. Thirdly, we explore which informant is most suitable to answer the DITS-items.

Part 3: Pilot Effect EMDR

Research period 2021-2022

In the second pilot, we will explore the effects of EMDR therapy in at least three adults with a severe ID using a multiple baseline design. For people with a severe ID, EMDR therapy is deemed most suitable because no active commitment of the client is expected outside of the sessions, and the appeal on their verbal skills is limited. Therefore the EMDR storytelling method, which was developed for children who are not able to report verbally about their memories, seems most suitable. EMDR therapy has proven effective in adults and children and there is increasing knowledge about the effects in people with a mild to borderline ID. Consequently, it could also be effective in people with a more severe ID.

The baseline measurements will take place while the clients are on the EMDR waiting list to avoid delays in the start of treatment. The effects on the PTSD symptoms and PTSD classification will be investigated by means of a weekly DITS-ID, the version for severe to moderate ID. Two or three target problems are monitored using a custom-made visual analogue scale which is filled in several times a week. The Behaviour Problems Inventory is used to investigate changes in problematic behaviour. It is filled in three times in total, during the baseline, the post intervention, and in the follow up phase. Changes in context that could influence the effects of the treatment are monitored with a weekly questionnaire that screens for changes in the team of caregivers, medication, day care, etc. All measurements are done with the same caregiver or relative, who also attends the EMDR-sessions.

Part 4: Adaptation and evaluation DITS-EVB

Research period: 2022-2023

The severe to moderate ID-version of the DITS-ID will be adapted based on the results of the first pilot, the reliability and validity will subsequently be investigated in a larger sample.