The other end of healthspan: self-directed healthy years and avoidable delay

A person cannot direct their own life from birth; that ability comes later. Delay in reaching it, part of what is studied as the transition to adulthood, can cost years of healthy, self-directed life without shortening life at all. It may come from economic hardship and other barriers, perhaps from family, or from a person's own avoidance. Life extension research mostly tries to move the end of healthy life later; this paper looks at the other end. I call the years a person is both healthy and self-directed, meaning ready and realistically able to direct their own life, self-directed healthy years. Growing up faster is not the aim, since very early parenthood is associated with worse later health and more education with lower mortality. I argue that delay has a cost that health expectancy measures do not separately show, and that part of it comes from obstacles a person cannot remove alone. Because self-direction here requires being realistically able, such obstacles delay it by definition; how large that delay is, and whether they also make people less ready, are empirical questions. Removing such obstacles could make more of a life's healthy years self-directed ones, without any biomedical discovery. That gain adds no years of life or health, so it complements geroscience and does not replace it. To make the argument testable, I define a population indicator and a measure of avoidable delay. Whether such delay can in practice be reduced, and whether reducing it would also improve later health, is untested, and I set out predictions that, if they fail, would show where the argument is wrong.