1. Slowing Aging Means Durably Reducing the Rate of Deleteriome Increase

To slow aging is to reduce the rate of deleteriome increase (and ideally preserve function and reduce disease and mortality risk) without simply trading one burden for another. In practice, this can mean enhancing maintenance and repair, reducing damage production, improving allocation of resources toward defense, or altering the environment that impacts deleterious change. In humans, the slope is expected to vary substantially across individuals because lifestyle, environment, disease burden, and exposures alter damage production, maintenance, reserve, and recovery. Slowing is about slope, not just state: a temporary improvement followed by the same rate is not slowed aging. Thus, the correct question for an intervention that slows aging is: does it durably flatten trajectories of biological age, functional decline, and mortality risk?