Persistent functional impairment as a preclinical signal of Alzheimer's disease: Advancing dementia prognostication through the natural history of function.

Early identification of Alzheimer's disease remains restricted due to overreliance on cognitive testing and biomarker accessibility. The study by Ghahremani et al. demonstrates that persistent, however not transient, functional impairment in cognitively normal older adults robustly predicts incident cognitive decline and dementia. This commentary positions their findings within social, behavioral, and public-health frameworks, emphasizing functional trajectories as ecologically valid, scalable markers of preclinical disease. By operationalizing function through persistence over time, this work advances dementia projections beyond cross-sectional assessment and supports integration of functional monitoring into population-level prevention, clinical trials, and equity-focused early detection strategies.