Page 135 - Post-traumatic stress disorder in adults with mild intellectual disability: Screening, assessment, and brief intensive EMDR therapy

General discussion
traumatic events that individuals with ID have been exposed to, which
hinders the identification of PTSD in this group (Hoogstad et al., 2024).
Another explanation why PTSD is often not recognised in adults with MID-BIF
may lie in the fact that when individuals with MID-BIF also have behavioural
problems (e.g., irritability, lethargy, stereotyped behaviour, aggression
towards others, or self-injurious behaviour), professional caregivers may
focus primarily on managing and regulating behavioural problems, which
can distract their attention from recognising possible PTSD symptoms
(McNally et al., 2021). This is particularly problematic given that PTSD and
behavioural problems are associated in people with MID-BIF, as observed
in Study 1 (Chapter 2) and as reported in other research (Mason-Roberts et
al., 2018; McNally et al., 2021; Rittmansberger et al., 2020).
The masking of PTSD symptoms by behavioural problems closely
resembles the phenomenon of diagnostic overshadowing, in which PTSD
symptoms are misattributed to the characteristics of ID or to symptoms
of other mental health disorders that are already diagnosed (Jopp & Keys,
2001; Wilsocki & Zalta, 2024). This phenomenon forms a third explanation
for why PTSD symptoms are often not recognised in adults with MID-BIF in
clinical settings. As a result of diagnostic overshadowing, PTSD symptoms
may be inaccurately attributed to symptoms of other mental health
conditions, such as autism, mood disorder, attention deficit hyperactivity
disorder (ADHD), or the ID itself. A notable proportion; that is, 30 out of 97
(31%) participants in Studies 1 and 2 (Chapters 2 and 3), had at least one
additional DSM-5 diagnosis (other than MID, BIF, or PTSD) recorded in their
client file, including autism spectrum disorder (21%), mood disorder (4%),
anxiety disorder (2%), personality disorder (3%), and ADHD (11%). This likely
increased the risk of diagnostic overshadowing in this group.
A contributing factor for not recognising PTSD in individuals with MID-BIF
is that the current PTSD guidelines do not sufficiently address individuals
with MID-BIF. While the multidisciplinary PTSD guidelines (Federatie
Medisch Specialisten, 2025) only briefly mention individuals with (M)ID,
they do not mention those with BIF. These guidelines do not include any
recommendations for screening, as the guidelines are aimed for the situation
when PTSD is already suspected. However, as demonstrated in Studies 1
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