Frailty as an underrepresented dimension in clinical trials of Alzheimer's disease therapies.

Population aging is redefining the clinical reality of Alzheimer's disease and increasing the need for outcome measures that reflect the complexity of older adults. Although recent trials on putative disease-modifying drugs have moved beyond cognition-only endpoints and now include integrated cognitive-functional measures, frailty remains underrepresented in trial design. We discuss the demographic context of aging societies, the relevance of frailty to dementia expression, and the implications of recent amyloid-β-targeting antibody trials, which include substantial numbers of older adults. We propose that frailty can improve external validity, refine biomarker interpretation, and strengthen precision medicine approaches linking biological measures with functional outcomes.