Delayed recall in dementia: sensitivity and specificity in patients with higher than average general intellectual...

Distinguishing early dementia from normal aging is especially difficult in patients with higher than average intellectual abilities. To find signs useful in determining that the elderly "worried and well" are not in an early phase of dementia, we compared the neuropsychological test performance of demented patients, patients who were not found to be demented, and control subjects.

A retrospective study of neuropsychological test results from persons over 50 years of age who had an age-adjusted verbal intelligence quotient (VIQ) greater than or equal to 110. Analysis of covariance (using age and education as covariates) was used to compare the normal, no dementia, and dementia groups. Significant differences were further analyzed using Tukey's post hoc procedure. Tests on which the three groups differed at ap < 0.01 level were included in multivariate analyses.

The no dementia patient group performed at functional levels comparable to those of the control group. By contrast, patients with dementia showed significant impairment on tests of memory, naming, and visuospatial function compared with both the control and no dementia groups. Immediate and delayed paragraph recall classified groups with a 96% specificity and 80% sensitivity in the multivariate discriminant analysis.

These results suggest that in patients with higher than average intelligence, the absence of a significant dementing process (as well as its presence) can be determined with reasonable probability.