Healthy Aging Across the Stages of Old Age.

Healthy aging is among the key frontiers for twenty-first century geriatrics and gerontology. Gerontology is positioned to address not only disease, debility, frailty, and death but also patients' hopes to remain healthy and high functioning and optimize their wellness. Definitions, models, and metrics of healthy aging are increasingly dynamic and multidimensional, drawing from biomedicine, social sciences, older adults' perspectives, and geroscience. Given current and projected demographics, focus on healthy aging at population, health system, research, clinical, and individual levels will lower costs and burdens while improving lives. Multiple models and strategies exist to guide progress in this critical emerging area.