> Part of that I think is certainly as you suggest, that the brain is a muscle, you need to use it to keep it fit. My claim, which admittedly is hard to substa

> Part of that I think is certainly as you suggest, that the brain is a muscle, you need to use it to keep it fit. My claim, which admittedly is hard to substantiate, is that growth (a general term) will offset aging to a much greater degree than people imagine. In fact, I wouldn't be surprised if psychological and physiological aging of the brain is mostly due to lack of growth. > To keep the muscle analogy, you won’t compete as an athlete at 72 no matter how fit you remain. I think the muscle analogy can be a useful one, but that it misleads here: Muscles start deteriorating at age 20 or 25; our brains do not on balance (they do in some ways, and improve in others). Peak mental performance is, IIRC, in our 40s and 50s.