Establishing the psychometric underpinning of cognition measures for clinical trials of Alzheimer's disease and its precursors: a new approach.

The Alzheimer's disease (AD) Cognitive Behavior Section (ADAS-Cog) is the most commonly used cognitive test in clinical trials of AD. Recent trials have focused on people earlier in the course of disease; however, there are concerns about using the ADAS-Cog at this crucial stage. Using data from the Alzheimer's disease Neuroimaging Initiative study, we used a range of traditional psychometric tests to evaluate those concerns. This issue of Alzheimer's & Dementia includes two articles that evaluate the ADAS-Cog. These articles report evaluations using two psychometric approaches: traditional methods and new methods. In this review, we provide accompanying background information to this program of research.