University of Birmingham, Division of Neuroscience, Department of Psychiatry, Queen Elizabeth Psychiatric Hospital, Birmingham
Welsh Centre for Learning Disabilities, Cardiff
Department of Sociology, Queen's University, Belfast
Department of Psychiatry, University of Leicester, Leicester, UK
Correspondence: Professor Shoumitro Deb, Division of Neuroscience, Department of Psychiatry, Queen Elizabeth Psychiatric Hospital, Mindelsohn Way, Birmingham B15 2QZ, UK. Email: s.deb{at}bham.ac.uk
Funding detailed in Acknowledgements.
Background Many adults with Down's syndrome develop Alzheimer's dementia relatively early in their lives, but accurate clinical diagnosis remains difficult.
Aims To develop a user-friendly observer-rated dementia screening questionnaire with strong psychometric properties for adults with intellectual disabilities.
Method We used qualitative methods to gather information from carers of people with Down's syndrome about the symptoms of dementia. This provided the items for the Dementia Screening Questionnaire for Individuals with Intellectual Disabilities (DSQIID), which we then tested for its psychometric properties.
Results The DSQIID was administered to carers of 193 adults with
Down's syndrome, 117 of whom were examined by clinicians who confirmed a
diagnosis of dementia for 49 according to modified ICD-10 criteria. We
established that a total score of 20 provides maximum sensitivity (0.92) and
optimum specificity (0.97) for screening. The DSQIID has sound internal
consistency (
=0.91) for all its 53 items, and good test-retest and
interrater reliability. We established a good construct validity by dividing
the items into four factors.
Conclusions The DSQIID is a valid, reliable and user-friendly observer-rated questionnaire for screening for dementia among adults with Down's syndrome.
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