DEVELOPMENT OF COGNITIVE INSTRUMENTS FOR USE IN CLINICAL-TRIALS OF ANTIDEMENTIA DRUGS - ADDITIONS TO THE ALZHEIMERS-DISEASE ASSESSMENT SCALE THAT BROADEN ITS SCOPE

The cognitive assessment protocol of the Alzheimer's Disease Cooperati ve Study (ADCS) was designed to evaluate the reliability and validity of cognitive assessment measures that might be valuable additions to t he Alzheimer's Disease Assessment Scale (ADAS) or other concise batter ies used in antidementia drug trials. As part of an overall ADCS proto col to develop new instruments to be used in trials of treatments for Alzheimer's disease (AD), patients with mild to moderate AD and cognit ively normal elderly were administered a battery of five tests at leas t three times over 1 year. The tests included word list learning with delayed free recall, a recognition memory test for faces, a series of letter and digit cancellation tests to measure concentration, tests of praxis, and a series of maze completion tasks designed to assess plan ning and executive function, A version of the digit cancellation task was reliable and sensitive to a broad range of dementia severity so th at it could provide a useful addition to the present version of the AD AS. Performance on the word learning task with delayed recall and a su bset of the mazes task were impaired even in mild AD, so these tasks m ay be useful in trials involving mild or at-risk subjects. Performance s on the facial recognition task and on the praxis tasks were not rela ted to dementia severity, so these tasks would not be useful to evalua te treatments. Therefore, the major outcome of this investigation was the identification of some potential addtions to the present ADAS that extend both the cognitive domains and the range of symptom severity c overed.