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MotionAge: A Deep Learning Framework for Biological Age Prediction from Wearable Activity
Proceedings of the 11th Machine Learning for Healthcare Conference, PMLR 340:1892-1920, 2026.
Abstract
Population aging is a major public health challenge, driving increasing burden from chronic disease and mortality. To better characterize individual health beyond chronological age, there is growing interest in biological age as a quantitative measure for risk stratification and longitudinal monitoring. Existing biological age models largely rely on laboratory or structured clinical data, limiting scalability and their ability to capture dynamic aspects of health. We propose MotionAge, a deep learning framework that learns a mortality-calibrated biological age directly from high-frequency wearable activity data. The framework combines deep sequence models with a wear-aware modeling strategy that explicitly represents observation reliability, allowing the model to distinguish device non-wear from observed inactivity in noisy and irregularly observed time series. Unlike prior wearable-based methods that predict chronological age or construct unsupervised biomarkers, MotionAge is trained to predict 5-year mortality risk and subsequently maps that risk onto an interpretable age scale. In NHANES accelerometry data, MotionAge achieved stronger mortality discrimination over chronological age and established benchmarks. Within fixed chronological-age bands, higher MotionAge acceleration was associated with lower activity and worse survival, with the largest separation observed among older adults. These results demonstrate that reliability-aware deep learning of wearable time series can yield scalable and interpretable aging phenotypes aligned with clinically relevant health outcomes.