Evaluation of screening tools for dementia in older adults with mental retardation.

We compared groups with and without diagnosed dementia matched on IQ, age, and presence of Down syndrome. The Dementia Scale for Down Syndrome and Dementia Questionnaire for Mentally Retarded Persons were used to assess participants. We developed two performance tasks to determine whether they were useful in separating subjects with and without dementia and also used the Reiss Screen. Both dementia scales and both performance tasks discriminated between groups. The dementia scales were not related to premorbid IQ, age, or gender, whereas performance tasks were related to dementia and IQ but not age or gender. Various Reiss Screen subscales also discriminated between groups. Subscales of the screening instruments and performance tasks were significantly related, indicating congruent validity. Logistic regression was conducted to assess which combination of tests discriminated best between groups.