The severe impairment battery: concurrent validity and the assessment of longitudinal change in Alzheimer's disease. The Alzheimer's Disease Cooperative Study.

Measurement of cognitive dysfunction in the early stages of Alzheimer's disease (AD) has been well studied and there are many objective tests in use for this purpose. However, with the exception of clinical rating scales, such as the Clinical Dementia Rating Scale, Global Deterioration Scale, and Functional Assessment Staging, there are few objective measures of cognition in the more advanced stages of AD. Given a renewed interest in potential AD therapies, objective measures of mental functioning are needed to adequately assess change in more advanced AD patients. As part of an effort by the NIA-Alzheimer's Disease Cooperative Study to evaluate new measures of efficacy for their utility in treatment studies, the Severe Impairment Battery (SIB) was examined in a 1-year evaluation of change across a wide range of AD severity. The data suggest that the SIB is a reliable and valid measure of progression, particularly in persons with moderate to severe AD. The SIB may therefore be a useful outcome measure in clinical trials that include patients with more advanced stages of AD.