TEST RE-TEST RELIABILITY OF THE CANTAB AND ISPOCD NEUROPSYCHOLOGICAL BATTERIES - THEORETICAL AND PRACTICAL ISSUES/

Neuropsychological test batteries are repeatedly administered to evalu ate changes over time or the effects of clinical interventions. Relati onships between scores on different tests within batteries are also ex amined to test models for associations between functional deficits. Th ese comparisons may be misleading unless Test/Re-test reliability for individual tests is satisfactory. Interpretations of repeated measurem ents also depend on the extent to which improvement with practice vari es between tasks and between more and less able individuals. Test/Re-t est correlations and practice effects for two neuropsychological rest batteries (CANTAB, ISPOCD) and from laboratory tasks commonly used in cognitive assessments;of older people were obtained from large groups of healthy elderly. Tests in neuropsychological batteries varied marke dly in test/re-test reliability which, in some cases: fell below level s considered methodologically acceptable. Putative measures of 'fronta l' or 'executive' function, in which performance may be markedly impro ved by abrupt discovery of an appropriate strategy, were especially li kely to show low reliability. Most tests showed significant practice e ffects, and on some these are substantial enough to compromise compari sons on repeated testing. On a minority of tests practice effects were counter-intuitive, in that less able showed significantly more gains than more able individuals. (C) 1998 Elsevier Science Ltd. All rights reserved.