LAUSR

Abstract Background A preponderance of behavioural symptoms is assumed to be the main difference in the manifestation of symptoms of post‐traumatic stress disorder (PTSD) in people with intellectual disability (ID). However, no study so far has assessed the relationship between challenging behaviour (CB) and PTSD. The present study aims to explore this relationship by exploring whether CB is directly related to trauma exposure or whether this relationship is mediated through core symptoms of PTSD. Methods Trauma exposure and current symptoms of PTSD were assessed in 43 adults with mild to moderate ID. Parallel versions were administered to 43 caregivers, including the Aberrant Behaviour Checklist to measure CB. Bayesian mediation analyses were conducted using self‐rated and informant‐rated data. Results The self‐report data showed no associations of CB with trauma exposure or PTSD symptoms. The association between informant‐rated trauma exposure and irritability was mediated by severity and frequency of PTSD symptoms. The associations between informant‐reported trauma exposure and the Aberrant Behaviour Checklist subscales hyperactivity and inappropriate speech were mediated by PTSD symptom severity. Conclusions The relationship between trauma exposure and CB was mediated by PTSD symptoms. PTSD core symptoms should be considered as underlying causes of CB, highlighting the necessity to explore trauma biography and symptoms of PTSD. The improvement of self‐report assessment in people with ID is an important task for future studies.