How Do Scores on the ADAS-Cog, MMSE, and CDR-SOB Correspond?

OBJECTIVE: Clinicians and researchers who measure cognitive dysfunction often use the Alzheimer's Disease Assessment Scale--Cognitive Subscale (ADAS-Cog), the Mini-Mental State Examination (MMSE), or the Clinical Dementia Rating scale (CDR-SOB). But, the use of different measures can make it difficult to compare data across patients or studies. What is needed is a simple chart that shows how scores on these three important measures correspond to each other. METHODS: Using data from 1709 participants from the Alzheimer's Disease Neuroimaging Initiative and item response theory-based statistics, we analyzed how scores on each measure, the ADAS-Cog, the MMSE, and the CDR-SOB, correspond. RESULTS: Results indicated multiple inflections in CDR-SOB and ADAS-Cog scores within a given MMSE score, suggesting that the CDR-SOB and ADAS-Cog are more precise in measuring the severity of cognitive dysfunction than the MMSE. CONCLUSIONS: This study shows how scores on these three popular measures of cognitive dysfunction correspond to each other, which is very useful information for both researchers and clinicians.