Measuring cognition in advanced Alzheimer's disease for clinical trials.

Measurement of cognitive dysfunction and treatment response in the early stages of Alzheimer's disease (AD) has used such scales as the Mini-Mental State Examination (MMSE) and the AD Assessment Scale (ADAS). With the exception of clinical rating scales, however, there are only a few objective measures of cognition for tracking progression in advanced AD. Given renewed interest in potential therapies for advanced AD, objective measures of cognition are important for the adequate evaluation of change due to AD progression or therapy. Several cognitive measures for advanced AD are reviewed. One measure, the Severe Impairment Battery (SIB) is reviewed in detail. Preliminary analyses from a trial of memantine show significant change on the SIB in memory (p < 0.001) and visuospatial functions (p < 0.02) over six-months with a trend for language and praxis. Data from a donepezil trial also highlight the importance of accurate assessment in advanced AD.