EFFECTS OF ADJUSTMENT ON THE CASE-FINDING POTENTIAL OF COGNITIVE TESTS

Adjustment of a cognitive test for an expected level of performance im proves the discrimination between brain diseased and healthy subjects. However, this improvement is subject to severe limitations and may be worthwhile only in clinical settings, where test results tend to be l ow regardless of disease status. The objective of this study was to pr ovide an empirical demonstration of these principles, applied to the d etection of dementia with the Mini Mental State Examination (MMSE). Th e subjects, derived from a population based sample, consisted of 36 ca ses of dementia (23 diagnosed shortly after testing and 13 at follow-u p 1 year later) and 301 nondemented subjects defined by a negative fol low up diagnosis. A simulated group of 179 clinically suspect normals was obtained by selecting all cases with an MMSE score below 27. Adjus tment was based on the Dutch version (DART) of the National Adult Read ing Test (NART), which was highly correlated (0.53) with the MMSE scor e of nondemented subjects. The results were in accordance with the pre dictions. We conclude that adjustment is unlikely to improve case find ing in representative samples, but can be profitable in clinical pract ice, where it will be especially helpful in ruling out cerebral diseas e.