In a healthy adult, domain-specific problem solving capacity will usually follow a curve in which there is an ascent in youth and a decline at older ages. The shape of that curve is determined by the balance of gains and losses. Gains are usually associated with learning, esp. learning via problem solving. Losses are mostly associated with health, esp. metal health, or neglect. As intelligence is a self-perpetuating quality, those who gain intelligence early may continue thriving into a very old age. On rare occasions, the effects of aging can be entirely compensated by lifelong learning, even in octogenarians and beyond.