This study sought to establish rate of decline of adaptive skills in a population of individuals with intellectual disability (ID) and dementia compared to similar persons without dementia, as well as examining the variability of positive and negative social behaviors across diagnostic classes. Among the general population, differential rates of functional decline have been established for normal aging and dementia. This knowledge assists in making differential diagnoses of dementia, establishing prognosis, and long-term planning.
For this study, participants in each group were individually matched for age, gender, Down’s syndrome status, and level of ID. Participants in the matched control group were screened for the presence of dementia with the Early Signs of Dementia Checklist (Visser & Kuilman, 1990). A 2 (groups) X 3 (measures) X 4 (repeated measures) Mixed Multivariate Analysis of Variance was completed to assess rate of decline within groups with the Vineland Adaptive Behavior Scales (Sparrow, Balla, & Cicchetti, 1984) and corresponding changes in positive and negative behaviors as measured by the Matson Evaluation of Social Skills for the Severely Retarded (Matson, 1995).
Hypothesis 1 established that prior to a diagnosis of dementia groups were equivalent (F (1, 40) = 1.086, p = .304). Hypothesis 2 found no significant differences for adaptive behaviors, therefore rate of decline was not established. However, visual analysis of plotted means supports predicted decline in skills for both groups. Furthermore there were significant differences across time for positive social skills as measured with the MESSIER (F (3, 96) = 3.887, p = .011, â = .811). Hypothesis 3 yielded significant correlations between the VABS and the MESSIER Positive domains. Hypothesis 4 resulted in no significant correlations between the VABS and the MESSIER Negative skills. The findings of Hypotheses 2, 3, and 4 provide support for the diagnostic utility of the MESSIER with dementia. However, Hypothesis 4 did not support different variances of negative behaviors across diagnostic groups. This would suggest that the measure of negative behaviors is not supported as a diagnostic tool at this time.