Page 21 - Post-traumatic stress disorder in adults with mild intellectual disability: Screening, assessment, and brief intensive EMDR therapy

General introduction
Diagnostic assessment of PTSD in adults with MID-BIF
There is growing attention in the literature regarding the assessment of
PTSD in individuals with MID-BIF (Hoogstad et al., 2025). Currently, the
Diagnostic Interview Trauma and Stressors – Intellectual Disability for adults
(DITS-ID-adults; Mevissen et al., 2018) is the only available instrument that
enables PTSD diagnosis based on the DSM-5-TR criteria (APA, 2022) in this
target group. This structured clinical interview showed good feasibility and
psychometric properties in a Dutch sample of adults with MID-BIF (Mevissen
et al., 2020a). The DITS-ID-adults demonstrated good inter-rater reliability.
Since there was no gold standard for assessing PTSD in individuals with
MID-BIF, Mevissen et al. (2020a) examined construct validity by analysing
the associations between PTSD diagnostic status, PTSD symptoms, and
symptoms of anxiety, depression, and subjective stress.
Although the DITS-ID-adults was found to be reliable and valid, this study
had a few limitations that should be noted. First, anxiety and depression
symptoms were measured using a proxy questionnaire, which may have led
to misinterpretation of symptoms owing to their subjective nature. Second,
behavioural problems were not assessed, whereas PTSD symptoms and
behavioural problems are known to be associated (Mason-Roberts et al.,
2018; McNally et al., 2021; Rittmannsberger et al., 2020). The DITS-ID-
adults is an important instrument for assessing PTSD in adults with MID-
BIF. Nevertheless, further research is necessary to strengthen the evidence
supporting its reliability and validity which is addressed in this dissertation
(Chapter 2).
PTSD treatment in adults with MID-BIF
Once PTSD is recognised and diagnosed in individuals with MID-BIF, it is
essential that they receive effective treatment. International guidelines for the
general population, such as those issued by the World Health Organization
(WHO, 2018) and the National Institute for Health and Care Excellence
(NICE, 2018), recommend Trauma-Focused Cognitive Behavioural
Therapy (TF-CBT) and Eye Movement Desensitisation and Reprocessing
(EMDR) therapy as first-line treatments for PTSD. This approach has been
endorsed and expanded in the Dutch multidisciplinary guidelines for PTSD
(Federatie Medisch Specialisten, 2025). The guidelines recommend that all
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