Assessing change in cognitive function in dementia: the relative utilities of the Alzheimer's Disease Assessment Scale-Cognitive Subscale and the Cognitive Drug Research system.

This paper considers the suitability of the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-cog) as the gold standard in registration trials of treatments for Alzheimer's disease. Working groups have recommended replacing the ADAS-cog if suitable automated alternatives can be found. This paper makes the case for the Cognitive Drug Research (CDR) computerised cognitive assessment system, as an example of a suitable instrument to replace the ADAS-cog. The CDR system has been widely used in dementia work for 20 years and shows good correlations to the ADAS-cog, while additionally assessing the domains of attention, working memory, information processing and retrieval speed of information held in memory. The utility of the system in evaluating and differentiating the major dementias will be described, as well as its ability to track deterioration over time. Its validation as a core measure of cognitive dysfunction in the dementias will be described, as will work showing that various CDR measures relate closely to activities of daily living. The sensitivity of the CDR system to anticholinesterases will be described in Alzheimer's disease, dementia with Lewy bodies and Parkinson's dementia. Finally, the CDR system has a large normative database which allows treatment effects in dementia to be put into an unambiguous clinical perspective. 2008 S. Karger AG, Basel