Who knows. I wish I could find the link, but I once read a study where some medical students took a bunch of people who were supposed to have Alzheimers and drastically reduced the number of medications that these elderly were taking. About half of the elderly returned to normal rationality. This would seem to indicate that many elderly don't have Alzheimers but instead are overwhelmed by overmedication.
I do know that my mother-in-law began to act like she was getting Alzheimers but the symptoms went away when my wife got her to stop taking Paxil. The doctor prescribed it to her shortly after 9-11 because she was getting upset after spending 3 straight days watching the Twin Towers collapse over and over on CNN. My wife cured her by making her turn off the TV, stopping the Paxil and taking long walks. One wonders how many other elderly are simply drugged into irrationality through overmedication.
So very true and have seen this with my own elderly parents. Some of the best "medication" is getting out and moving about plus regular B-12 shots work absolute wonders.