Mind you, this book is 10+ years old but that's not exactly the impression I got from it. That is, the brain __is plastic__ and __does__ have a high capacity for "re-configuring" itself. The story of the woman who was born with only one hemisphere of here brain comes to mind. There are other examples as well in the book.
"The Brain That Changes Itself: Stories of Personal Triumph from the Frontiers of Brain Science"
You can have pretty much the same mental condition when you are 70-80 years old as when you are 20-30. But to have that you need to keep using your brain and challenging it. Old people usually have much less opportunity to stay mentally active. And less motivation.
Statements above are based mostly on The Brain That Changes Itself by Norman Doidge[1] which I highly reccomend. Plus just listen to some old folks that you can tell are still quick - Warren Buffet 86, Chomsky 88, James Harris Simons 79 and so on.
The book "The Brain that Changes Itself" sites a number of examples that often border on the bizarre.
https://www.amazon.com/Brain-That-Changes-Itself-Frontiers/d...
"The Brain That Changes Itself: Stories of Personal Triumph from the Frontiers of Brain Science"
https://www.amazon.com/Brain-That-Changes-Itself-Frontiers/d...
Statements above are based mostly on The Brain That Changes Itself by Norman Doidge[1] which I highly reccomend. Plus just listen to some old folks that you can tell are still quick - Warren Buffet 86, Chomsky 88, James Harris Simons 79 and so on.
1. https://www.amazon.com/Brain-That-Changes-Itself-Frontiers/d...