What is the clinically relevant change on the ADAS-Cog?

Area of Science:

• Neurology
• Clinical Trials
• Cognitive Assessment

Background:

• Alzheimer's disease (AD) diagnosis and progression require reliable measures of cognitive change.
• The Alzheimer's Disease Neuroimaging Initiative (ADNI) provides a valuable dataset for studying AD progression.
• Establishing minimal clinically relevant change (MCRC) is crucial for interpreting trial results.

Purpose of the Study:

• To determine the minimal clinically relevant change (MCRC) on the Alzheimer's Disease Assessment Scale-Cognitive (ADAS-Cog) for individuals with mild Alzheimer's disease (AD).

Main Methods:

• A cohort study design was employed using data from the Alzheimer's Disease Neuroimaging Initiative (ADNI).
• Anchor-based methodology compared ADAS-Cog changes to clinician judgments of worsening across four domains over 6-month and 6-12 month intervals.
• Distribution-based measures, including half-baseline standard deviation (1/2 SD) and standard error of the mean (SEM), were calculated to support findings.

Main Results:

• Analysis of 181 patients showed an average ADAS-Cog change of 3.1-3.8 points for those with clinically significant worsening between baseline and 6 months.
• Similar results were observed for 177 patients analyzed over the 6-12 month interval.
• Distribution-based measures indicated a 1/2 SD of 3.2 and SEM of 3.7 for baseline ADAS-Cog scores.

Conclusions:

• A 3-point decline on the ADAS-Cog may represent a minimal clinically relevant change (MCRC) for early AD patients in clinical trials.
• Further research is recommended to establish MCRC for improvement on the ADAS-Cog.
• Additional studies are needed to define the minimal clinically relevant difference between treatments using patient-based anchors.