There's a basic, common sense sort of logic to "use it or lose it". If you exercise something, it stays fit and toned. I believe there's been a variety of research for some time pointing in the direction of 'mental exercise' having profound effect on the brain.
F'instance, the stereotype of middle-aged to older people being inflexible and upset/scared/uncomfortable with shockingly different ideas than those they are familiar with, is blasted by some older people who have flexible mindsets and a capacity for absorbing new information. I know some older men and women like this, and in most cases I have observed that they have engaged in creative and/or flexibile behavior, lifestyles, and hobbies. Most older persons who fit the stereotype I personaly have encountered, seem to be those who fall prey to the cultural momentum to 'box up' the stages of a person's life and treat everyone more or less the same. You work 40 years at a repetative job, retire, go to the senior home, and play cards while eating the same vanilla pudding as everyone else.
