Samantha Bouwmeester

Background: Individuals with severe intellectual disabilities (SID; IQ 20–35) are believed to be at heightened risk of developing posttraumatic stress disorder (PTSD). However, research targeting trauma treatment in individuals with SID remains limited, and controlled intervention studies are scarce.

Introduction: Until recently, no diagnostic instrument was available to classify posttraumatic stress disorder (PTSD) in individuals with severe or moderate intellectual disability (SID). This study investigates the Diagnostic Interview Trauma and Stressors–Severe Intellectual Disability (DITS‐SID), a caregiver‐administered interview corresponding with DSM‐5(TR) PTSD criteria for children ≤ 6 years. Interrater reliability and convergent and content validity were examined. Methods: The DITS‐SID, Aberrant Behavior Checklist (ABC) and Child and Adolescent Trauma Screener 3–6 (KJTS 3–6) were administered to relatives and professional caregivers of 97 adults with SID. Results: Interrater reliability was good to excellent. Convergent validity was supported by correlations with ABC and KJTS 3–6 scores. Content validity appeared good as adults who met PTSD symptom criteria had, on average, higher interference scores, higher DITS‐SID atypical symptom scores and a greater number of experienced traumas and stressors. No association was found between meeting PTSD symptom criteria and PTSD criterion A. Conclusion: The DITS‐SID appears feasible for classifying PTSD in adults with SID. Future research should evaluate its validity in children with SID.

Schema therapy (ST) is an effective psychotherapy for personality disorders in (older) adults. There is an increasing awareness of the imbalance in the ST community because of the emphasis on negative schemas versus attention to positive schemas. This study aimed to evaluate the effectiveness of an adapted ST approach that integrates positive schemas. Using a multiple baseline design, the study assessed 10 older adults (aged > 60) with Cluster C personality disorders through 1 year of weekly individual ST sessions, followed by a 6‐month follow‐up. Baseline consisted of 4–8 weeks without intervention. Primary outcomes were credibility of positive and negative core beliefs; secondary measures examined symptomatic distress, schema modes, early maladaptive and positive schemas. Results showed mixed individual outcomes. Positive core beliefs significantly improved in 38% of participants during treatment and 50% at follow‐up, whereas negative core beliefs decreased significantly for 25% of participants during treatment and 67% at follow‐up. At the group level, significant increases with very large effect sizes were observed in positive core beliefs in baseline versus follow‐up and reductions in negative beliefs in baseline versus treatment and versus follow‐up. Secondary outcomes revealed significant reductions in symptomatic distress and PD criteria, alongside increased positive schemas. No significant changes were found for schema modes or maladaptive schemas. This first study underscores the potential of integrating positive schemas into ST for older adults, suggesting preliminary efficacy. Further research is essential to generalize findings across different age groups and diagnoses and to identify which aspects of positive schemas enhance therapy outcomes.

A recent Delphi study found expert-consensus that clinical staging (CS) could provide a valid framework in the assessment of personality disorders (PDs) in older adults (Conjaerts et al., 2025). The categorical models used currently to assess PDs are poorly suited for treatment selection, in older adults even more so as age-specific factors were not considered in the development. The aim of this study was to investigate the interrater reliability, sensitivity and specificity of the recently proposed CS model, using the level of personality functioning and the lifetime course of personality pathology as profilers. Clinical vignettes were composed to reflect various stages of PD. 35 international expert clinicians in the field of PDs in older adults were presented three vignettes and asked to assign the PD to a clinical stage. Interrater reliability was good (κ = .86; 95% CI: 0.79-0.94). Overall sensitivity (0.80) and specificity (0.93) rates of the model were good. Sensitivity for stages 2, 3 and 4 was very good (0.92, 0.85, and 0.85, respectively), whereas sensitivity for stage 1 was insufficient (0.60). The overall satisfactory interrater reliability, sensitivity and specificity rates indicate that CS might be a valid and reliable new approach of assessing PDs in older adults.

Street Temptations is a virtual reality-enhanced training program developed as an add-on intervention for adolescents with disruptive behavior problems. Using mentalization as a primary treatment mechanism, the program aims to address cognitive distortions and increase motivation for behavior change. This study provides an initial evaluation of Street Temptations in a forensic youth care setting, utilizing both quantitative and qualitative data within an A-B-A’ single-case experimental design. Throughout a baseline, intervention, and follow-up phase, adolescents completed daily measurements on cognitive distortions and motivation for behavior change. Secondary outcomes were assessed before baseline, after intervention, and after follow-up, which included mentalization and perspective-taking. Qualitative data were collected after the intervention through separate interviews with adolescents and Street Temptations therapists. A total of 8 adolescents were included in the study, 5 of whom dropped out, leaving 3 who provided sufficient data for visual inspection of the outcomes. The observed patterns suggested an increase in adolescents’ awareness of others’ perspectives during participation in Street Temptations, potentially indicating a positive effect on cognitive distortions. However, daily assessments did not show an increase in adolescents’ motivation for behavior change. Positive effects of Street Temptations and virtual reality, as well as areas for improvement, were highlighted in all interviews. Recommendations for further development and implementation are discussed. Overall, this study provides preliminary support for the use of Street Temptations as an add-on intervention in forensic youth care.

Summary: Key mechanisms of change in cognitive behavioural therapy for insomnia in the general population encompass changing sleep‐related beliefs and behaviours. In a population with acquired brain injury, cognitive behavioural therapy for insomnia is effective as well, but little is known about the mechanisms of change. The aim of this study was to evaluate how changing sleep‐related beliefs and behaviours were associated with improvement in insomnia following blended cognitive behavioural therapy for insomnia in a population with acquired brain injury. A secondary analysis was performed on data of a randomized–controlled trial, including 24 participants that received blended cognitive behavioural therapy for insomnia, and 24 participants that received treatment as usual. Results showed that following blended cognitive behavioural therapy for insomnia, significantly more participants improved on dysfunctional beliefs and sleep‐related behaviours and this was associated to improvement in insomnia severity. For sleep‐related behaviours, the association between improvement on behaviour and improvement on insomnia was significantly moderated by blended cognitive behavioural therapy for insomnia. However, the relation between dysfunctional beliefs and insomnia was not moderated by type of treatment. Similar results were found for acquired brain injury‐adapted versions of the questionnaires in which up to half of the items were excluded as they could be regarded as not dysfunctional for people with acquired brain injury. These results show that improvement on insomnia severity is related to improvement in dysfunctional beliefs and behaviours, and cognitive behavioural therapy for insomnia efficacy may be moderated by the improvement in behaviours in particular. A focus on these behaviours can enhance treatment efficacy, but caution is needed regarding the behaviours that may reflect adequate coping with the consequences of the acquired brain injury.

Dementia is related to disturbances in the sleep-wake pattern, behavioural and psychological symptoms of dementia (BPSD). These phenomena are the main reason for institutionalization. Assistive light technology is relevant to study, as mitigation of BPSD may allow for the improvement of quality of life for both people with dementia and their caregivers. Studies of dynamic light exposure in home-dwelling populations are scarce. In this single-case experimental design study, we evaluated the effects of exposure to dynamic light on the sleep-wake pattern and symptoms of depression, agitation, and anxiety in 11 home-dwelling people with dementia. A four-phase light-exposure therapy oscillating between the control and intervention waves was offered. Objective and questionnaire data were analysed and discussed. The results show that the used dynamic light system did not significantly affect the sleep variables. The severity of BPSD fluctuated in the expected pattern, reducing in intensity with increased light exposure. This pattern was significant for depression and agitation. This longitudinal study included an exploration of a low-cost assistive light intervention within a hard-to-study home-dwelling dementia population. The lessons learned are discussed and recommendations are made for future studies, as this design seems suitable for studying lifestyle interventions to support home-dwelling people with dementia.

A randomization test can be used to statistically test hypotheses in multiple baseline designs to complement the commonly used visual inspection analysis. A crossed factor simulation study was performed to investigate the power of a randomization test in an multiple baseline design. The results show that the degree of autocorrelation of the observations, the number of participants, the effect size, the overlap of possible start moments of the intervention between participants, the ratio of the number of measurements in the baseline- and intervention phase, a gradually emerging effect, and the number of measurements had strong main effects on the power. The two-way interactions between number of participants and effect size, and between the number of measurements and the number of start moments of the intervention also had a large effect. An online tool was developed to calculate the power of a multiple baseline design given several design characteristics.