Diana B. Burt

Dementia in adults with Down syndrome: Diagnostic challenges

Although dementia associated with Down syndrome is often presumed to be progressive and irreversible, variations in disease course have been described. In addition, prevalence rates have varied widely among studies. This interim report is a description of the status of 70 adults with Down syndrome who are being followed for signs of dementia. Of the 70, 12 met all criteria for dementia, 40 met subsets of criteria, and 18 met no criteria. Information is provided on instruments used, rationale for choice and revision of instruments as well as criteria used to identify dementia and changes in the status of the participants. The results suggest that extreme care is needed when diagnosing dementia in adults with Down syndrome, for both clinical and research purposes.

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.

Aging in adults with intellectual disabilities.

A cross-sequential design was used to examine changes related to aging in adults with and without Down syndrome (ns = 55 and 75, respectively). Adults received yearly neuropsychological and medical evaluations. Support for precocious aging in adults with Down syndrome was evident only on a test of verbal fluency, with weaker support obtained on a test of fine-motor skills. Cross-sectional age differences for all adults were obtained on tests of memory and community living skills. General intellectual level, gender, and psychiatric status were consistently related to performance, indicating the need to examine such mediating variables in studies on aging.

Assessment of orientation: relationship between informant report and direct measures.

Although informant reports of everyday functioning are often used in dementia assessments, the actual correspondence between such indirect reports of functioning and actual performance has not been examined. Orientation results on the Dementia Questionnaire for Mentally Retarded Persons were compared to those obtained in direct assessment of orientation of 138 adults with mental retardation. Fair to good agreement was found between informant report and direct assessment. However, for some orientation items, nonverbal IQ, cause of mental retardation, and age affected the level of agreement. Thus, both informant report and direct measures of orientation are necessary in dementia assessments, and further work is needed on informant scale validation.

Triazolam and ethanol effects on human matching-to-sample performance vary as a function of pattern size and discriminability

The effects of placebo, triazolam (2.0, 4.0 and 8.0 micrograms/kg) and ethanol (0.25, 0.5, 1.0 g/kg) on perceptual-motor performance were examined using a visual pattern matching-to-sample procedure in which pattern size and comparison stimulus discriminability were systematically varied. Baseline response rates and accuracy increased as the discriminability of the comparison stimuli increased. At the highest dose, both drugs decreased response accuracy. This disruption of accuracy was attenuated by increasing the discriminability of non-matching stimuli. Triazolam produced dose-related decreases in response rate while ethanol produced only slight decreases at the highest baseline rates of responding. Thus, triazolam produced response rate slowing at relatively lower doses than ethanol.