Background: The USA National Task Group (NTG) guidelines advocate the use of an
adapted version of Dementia Screening Questionnaire for Individuals with Intellectual Disabilities
(DSQIID) for dementia screening of individuals with Down syndrome (DS) and with other forms of ID
Objective: In order to meet these guidelines, this study verifies the psychometric properties of an Italian
version of the original DSQIID in a population composed of adults aged 40 years and over with DS and
Methods: Internal consistency, inter-rater and intra-rater reliabilities, structural validity, convergent validity
and known group differences of DSQIID-I were assessed with 200 individuals with ID (mean of
55.2 years; range: 40-80 years) recruited from 15 different centers in Italy. Diagnosis of dementia was
done according to IASSID diagnostic criteria and its degree of clinical certainty was defined according
to Silverman et al.’s classification (2004).
Results: Cronbach’s alpha for the DSQIID-I was 0.94. The ICCs for inter-rater and test-retest reliability
were both 0.89. A Principal Component analysis revealed three domains, namely memory and confusion-
related items, motor and functional disabilities, depression and apathy, which explained almost
40% of the overall variance. The total DSQIID-I score correlated significantly with DMR and differed
significantly among those individuals (n = 34) with cognitive decline from those without (n = 166). Age,
gender and severity of ID were unrelated to the DSQIID-I.
Conclusion: The present study confirms the cross-cultural value of DSQIID which was proved to be a
psychometrically valid and user-friendly observer-rated scale for dementia screening in adults with both
DS and non-DS ID.