Cross‐sectional and longitudinal assessments of function in prodromal‐to‐mild Alzheimer's disease: A comparison of the ADCS‐ADL and A‐IADL‐Q scales

INTRODUCTION: Prior observational work in a heterogeneous cohort of participants with mild cognitive impairment suggests the Amsterdam Instrumental Activities of Daily Living Questionnaire (A‐IADL‐Q) may have greater sensitivity for functional decline than the more established Alzheimer's Disease Cooperative Study–Activities of Daily Living (ADCS‐ADL) scale. However, the relative utility of the A‐IADL‐Q versus the ADCS‐ADL for clinical trials in early Alzheimer's disease (AD) remains uncertain. METHODS: We compared baseline and longitudinal performance of the A‐IADL‐Q and ADCS‐ADL in participants with biomarker‐confirmed prodromal (pAD; n = 158) or mild (mAD; n = 283) AD enrolled in the 18‐month Tauriel study of semorinemab (NCT03289143). RESULTS: The A‐IADL‐Q exhibited numerically stronger discrimination between pAD and mAD participants at baseline per Cohen's d analyses and similar sensitivity to longitudinal decline across cohorts over 18 months relative to the ADCS‐ADL. DISCUSSION: The comparable performance of the ADCS‐ADL and A‐IADL‐Q supports the utility of the A‐IADL‐Q in early AD clinical trials. HIGHLIGHTS: The Amsterdam Instrumental Activities of Daily Living Questionnaire (A‐IADL‐Q) may be more sensitive than the Alzheimer's Disease Cooperative Study–Activities of Daily Living Scale (ADCS‐ADL) for distinguishing prodromal and mild Alzheimer's disease (AD). A‐IADL‐Q and ADCS‐ADL are similarly sensitive to decline in early AD over 18 months. Comparable performance of these indices supports A‐IADL‐Q use in future AD trials. Additional AD clinical trial data could extend findings across more diverse cohorts.