Haven't seen the program, as I've never had TV. But I remember in class years ago, our tutor talked about a study that was done on a group of nuns (because of similar lifestyle over a long number of years, I think - they made a good control group)- as they aged. And after death, it was actually found that the Reverend Mother's brain showed the placques of advanced alzheimer's disease - but she had showed no symptoms. She had been a lifelong scholar of languages, and of course in the convent, they also sang a lot, their habits were extremely regular, with exercise built into every day, plus she did translation work - so they came to the conclusion that her very high intellectual ability, her lifelong learning & education, plus the regularity of her daily life, the exercise, the singing etc. all worked to enable her brain to just bypass the disease for long enough that it never affected her noticeably. My own husband was able to "hide" or bypass his symptoms for years too, and he had also been a lifelong scholar, who spoke several languages. He was well into the middle stages of the disease before it became really noticeable to others. There had been changes in his personality - his paranoia had increased. But the memory problems, the problems with words - he was able to sidestep those for years. His consultant explained it like this: He said that the more active we are, mentally & physically, the more neural pathways our brain builds (and he included things like spending time in nature, meditation in "activity"). So, when alzheimers' disease starts damaging the brain, and we come against a "block" - the brain can just divert along a different neural pathway - and can continue to do that for much longer, the more pathways we have.
Unfortunately, for William, once he reached a certain point, it seemed as if his decline was pretty rapid then - but his consultant said it wasn't really. It was just that he could no longer "divert" any more - there weren't enough neural pathways left undamaged anymore. So it seemed like a sudden deterioration, when in fact he had just reached the middle/later stage.
