Any sufficiently large body of biological data taken from individuals at varying ages can be used to produce an aging clock via machine learning techniques. The clock provides a measure that should reflect biological age, the burden of cell and tissue damage and consequent risk of dysfunction, but that isn't a given and must be assessed for any new clock. Researchers have been creating new clocks from varied types of data at a fairly rapid pace for some years now. Here, researchers use data on blood flow obtained from consumer devices worn on the wrist. Photoplethysmography is the formal name for the use of devices that illuminate the skin and measure changes in light absorption in order to assess parameters of blood flow, and the growing popularity and low cost of these devices have given rise to large databases suitable for the development of aging clocks.
Aging biomarkers play a vital role in understanding longevity, with the potential to improve clinical decisions and interventions. Existing aging clocks typically use blood, vitals, or imaging collected in a clinical setting. Wearables, in contrast, can make frequent and inexpensive measurements throughout daily living. Here we develop PpgAge, an aging clock using photoplethysmography at the wrist from a consumer wearable.
Using the Apple Heart and Movement Study (n = 213,593 participants; >149 million participant-days), our observational analysis shows that this non-invasive and passively collected aging clock accurately predicts chronological age and captures signs of healthy aging. Participants with an elevated PpgAge gap (i.e., predicted age greater than chronological age) have significantly higher diagnosis rates of heart disease, heart failure, and diabetes. Elevated PpgAge gap is also a significant predictor of incident heart disease events (and new diagnoses) when controlling for relevant risk factors. PpgAge also associates with behavior, including smoking, exercise, and sleep. Longitudinally, PpgAge exhibits a sharp increase during pregnancy and concurrent with certain types of cardiac events.
Link: https://doi.org/10.1038/s41467-025-64275-4
View the full article at FightAging
