Page 132 - Post-traumatic stress disorder in adults with mild intellectual disability: Screening, assessment, and brief intensive EMDR therapy

Chapter 6
therapists for adults with MID-BIF and severe behavioural problems who
were classified with PTSD. Fourth, to explore the experiences of three
individuals with MID-BIF and severe behavioural problems who received
this treatment.
This chapter summarises the four studies included in this dissertation and
highlights two key findings: “PTSD can be recognised in adults with MID-
BIF through the Trauma Screener – Intellectual Disability (TS-ID)” and “Brief
intensive EMDR therapy with rotating therapists was effective in our group
of adults with MID-BIF, PTSD, and severe behavioural problems”, and ends
with the conclusion.
Summary of chapters
The first study, as described in Chapter 2, assessed the reliability and
construct validity of the DITS-ID-adults (Mevissen et al., 2018) in 97 adults
with MID-BIF living in supported housing. The interrater reliability of the
DITS-ID-adults proved good to excellent. The construct validity of the
DITS-ID-adults was good, based on positive correlations between the Brief
Symptom Inventory –18, revised Dutch version (BSI–18), Impact of Event
Scale-Intellectual Disability (IES-ID), Anxiety, Depression, and Mood Scale
(ADESS) and DITS-ID-adults, and mainly positive correlations between the
Behavior Problems Inventory (BPI) and DITS-ID-adults (r = .21 to r = .75).
Furthermore, it was found that reporting potentially traumatic events listed
under the DSM-5-TR A criterion for PTSD was associated with fulfilling
PTSD symptom criteria. A large proportion of participants met PTSD criteria
(58%), while only 7% had a documented PTSD diagnosis in their clinical file
prior to participation in the study. These findings highlight the urgent need
to improve PTSD recognition in individuals with MID-BIF.
The second study, detailed in Chapter 3, evaluated the adult self-report
and proxy versions of the Trauma Screener–Intellectual Disability (TS-ID),
which were adapted from the Dutch Child and Adolescent Trauma Screener
(Dutch abbreviation KJTS; Kooij et al., 2025; CATS-2; Sachser et al., 2022),
for use in adults with MID-BIF. The adult self-report version showed high
internal consistency (Cronbach’s α = .94) and excellent validity (AUC =
.94) in distinguishing PTSD in adults with MID-BIF. Optimal specificity
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