Utility of Clinical Trial Batteries in the Measurement of Alzheimer's and Huntington's Dementia

Abstract

Tests used as outcome measures in clinical trials of antidementia agents are not typically employed as part of diagnostic evaluations, and little information exists as to the sensitivity of these tests in terms of either differentiating demented patients from normal individuals or in distinguishing dementias of various types and etiologies. Sensitivity to mild dementia and sensitivity to impairment of various neuropsychological domains are, however, prerequisites for valid use of an instrument as an outcome measure in this context. The present study was undertaken to directly compare six different tests (three traditional psychometric tests and three clinical trial batteries) in terms of their sensitivity to detect and distinguish between mild dementia in patients with either Alzheimer's disease (n = 15) or Huntington's disease (n = 15), when compared to normal controls (n = 15). Tests included the Mattis Dementia Rating Scale, the Mini-Mental State Examination, the Wechsler Memory Scale-Revised, the Alzheimer's Disease Assessment Scale-Cognitive Subscale, the Computerized Drug Research (CDR) Cognitive Assessment System, and the Repeatable Battery for the Assessment of Dementia (RBAD). All of the tests were roughly equivalent in terms of their ability to discriminate normal subjects from mildly demented patients. Only the CDR and RBAD, however, were able to reliably discriminate between the two patient groups. The results are discussed in terms of the applicability of these tests as outcome measures for clinical trials in dementing disorders.