Investigation of dementia screening tools in a cohort with Down syndrome and intellectual disability
Objectives: The following thesis is presented within two separate pieces of work. A systematic literature review (SLR) aimed to evaluate the individual characteristics and psychometric properties of four dementia screening tools. These were the Dementia Questionnaire for People with Learning Disabilities (DLD) (Evenhuis, 2007), the Dementia Scale for Down Syndrome (DSDS) (Gedye, 1995), the Dementia Screening Questionnaire for Individuals with Intellectual Disabilities (DSQIID) (Deb et al, 2007a) and the Adaptive Behaviour Dementia Questionnaire (ABDQ) (Prasher et al, 2004). The empirical research (ER) aimed to evaluate the clinical utility and longitudinal accuracy of two of these tools; the DLD and the ABDQ in a clinical population with intellectual disability (ID) and Down syndrome (DS). Methods: For the SLR a comprehensive list of electronic academic databases were searched to identify studies which included information relating to the psychometric properties of the DLD, DSDS, DSQIID and the ABDQ. Information within the studies was then extracted and rated using two quality assessment measures. These were the Characteristics of Assessment Instruments for Psychiatric Disorders in Persons with Intellectual Developmental Disabilities (CAPS-IDD) (Zeilinger et al, 2013b) and the Qualsyst (Kmet, 2004). For the ER, a repeated measures MANOVA was used to assess change over time between two groups of people with intellectual disabilities and Down syndrome; one with dementia and one without. Results: In the SLR, 16 studies were identified and rated using the CAPS-IDD and the Qualsyst. Detailed information related to the dementia screening tools and quality ratings of the papers are provided. In the ER both the ABDQ and the DLD demonstrated a clear difference between those who develop dementia and those who do not, with those in the ‘dementia’ group exhibiting increasing scores over time. Conclusions: The SLR concludes that the evidence base for these dementia screening tools remain limited. The largest evidence base was evidenced for the DLD. The ER concludes that the ABDQ and the DLD are useful tools to differentiate between those who develop dementia and those who do not. Further analysis incorporating the exploration of individual component items of tools is recommended.