PhD defence J.G. (Jeanet) Nieuwenhuis

Dissertation in short:

The purpose of this thesis was to investigate the prevalence of Mild Intellectual Disability (MID) and Borderline Intellectual Functioning (BIF) and to study the associations of MID/BIF with other mental health outcomes in different settings in general psychiatry. The prevalence of MID/BIF in general psychiatry in the Netherlands and most other countries was largely unknown until the start of the projects included in this thesis. In general, although the attention of this patient group is growing, MID/BIF often seems to go undetected and is not recognised in clinical practice. The results of the studies presented in this thesis attempt to contribute to an earlier recognition, leading to better treatment. In all studies presented in this thesis, we used the SCreener for Intelligence and Learning disability (the SCIL) to access intelligence in the range of an IQ of 50-85 (MID/BIF).

The research questions addressed in the thesis were the following:

1. What is the estimated prevalence of patients suspected of MID/BIF using the SCIL as a screener on admission wards? (Chapter 3)
2. Are patients screened positive for MID/BIF with the SCIL more often subjected to coercive measures than patients who screened negative? (Chapter 3)
3. What is the estimated prevalence of patients suspected of having MID/BIF in different mental health care settings using the SCIL as a screener? (Chapter 4)
4. What percentage of patients who screened positive for MID/BIF are suspected of having cognitive decline, using the SCIL as a screener? (Chapter 4)
5. Are patients who screened positive for MID/BIF using the SCIL as a screener more often engaged in aggressive incidents than patients not suspected of having MID/BIF? (Chapter 5)
6. Do patients suspected of MID/BIF more frequently experience trauma and have Post-Traumatic Stress Disorder (PTSD) symptoms compared to patients not suspected of having MID/BIF? (Chapter 6)
7. Finally, we tried to answer the research question: what is the association between the level of psychiatric symptoms and the scores on the SCIL? (Chapter 7)