Thursday, 3 April 2003

This presentation is part of : Detection of dementia in clinical and community settings

Early Detection and Differential Diagnosis of Alzheimer’s Disease (AD) Using the CANTAB Paired Associates Learning Test

Henry O'Connell, Mercer’s Institute for Research on Ageing, Dublin, Ireland

Objective: The CANTAB battery of computerized neuropsychological tests includes Paired Associates Learning (PAL), which has recently been shown to accurately discriminate early AD form depression and normal controls. The objectives of the present study were to evaluate the utility of the PAL test (i) as a diagnostic tool for the early detection of AD (ii) in differentiating AD from depression and normal controls.

Design: Retrospective cross-sectional comparison of three groups of MIRA memory clinic attenders.

Materials and Methods: PAL sensitivity and specificity in discriminating between n=34 AD, n=27 depressed and n=16 normal control cases was evaluated using recommended cut points. In addition, PAL was compared to the delayed word recall (DWR) test in the AD group.

Results: PAL, AD vs normal controls: Sensitivity = (23/34) 68%, Specificity = (16/16) 100% Overall accuracy = 78% PAL, AD vs depression: Sensitivity = (23/34) 68%, Specificity = (22/27) 82% Overall accuracy = 74%

PAL vs DWR, n=16 AD: PAL Sensitivity = (9/16) 56%. DWR sensitivity = (15/16) 94%

Conclusion: In discriminating AD from normal controls specificity was excellent. It was lower but still high in discriminating AD from depression. However, sensitivity was moderate at less than 70% for both comparison groups. In a small sub-sample, DWR was superior to PAL in identifying early AD cases.

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