Interesting. Do you have a source for that?
My mother, at 85, has a dance group she attends every week. She also rides a bicycle almost every day, takes walks, swims, drives a stick shift... While there are problems with her spine (she’s shrunk well over an inch the past few years) which lead to occasional leg pains, she’s generally holding up well. Does a lot of sudokus, crossword puzzles etc. too, to stimulate the brain.
I am the original source for this information — as self-evident truth that can be tested (verified) by anyone inclined to do so. That is what “science” is — and not looking for authority to tell them so, which is what you’re asking. If you want to be the first to know an original idea, then there will be no other source to turn to. But if you want to be the last to know about anything, there will be many sources — usually all plagiarizing and repeating what the original said many volumes ago. That is how most physical fitness experts come upon their knowledge and “expertise” — but by then, is usually all wrong.
I was also the source for the insight that mouth-to-mouth resuscitation was totally unnecessary and would preclude people from giving first aid in the age of AIDS. Some people are the original thinkers on any subject matter — but they leave a logical path for thinking through and testing these ideas — to arrive at their own independent conclusions — because it is worthless if I or any other person says it is true, when it obviously doesn’t work — and especially doesn’t work for you, which is the only thing that matters. That is reality.
Having been regarded as “one who spoke with authority,” among the “experts,” your description of your mother’s condition and activities are fairly common — by as I’m pointing out, the reason “mental” exercises will ultimately fail to achieve the objective of keeping the mind (brain) healthy is the problematical lack of flow produced by the movement of the head that causes an alternating muscle contraction and relaxation as indicated by the atrophying of the neck muscles in most older people, and even most people in the population at large.
Even if one is bike-riding, there is very little or no movement at the wrists or the neck — and so if done for hours at a time, daily, one notice numbness developing at the hands — extending up through the arms. The same thing is also happening to the head — but less noticeable. Treadmilling is also the same thing. No movement at the wrists, neck/head — which is what is specifically indicated and required to maintain the health of those critical extremities of the body.
The beauty of forums like Free Republic is that there are no “fact checkers” with the presumption that they know all that can be known, and so they censor, suppress, edit, and all the shenanigans of publications maintaining their control and preeminence in that field — and limiting the discussion to only what they know — and wish to confirm. Science is not only proving one’s hypothesis but also disproving it as well.