The weekend edition of the News Sentinel contained a article about an elderly man who paid $5,000 as a "claim fee" when he was told that he had won a contest. His statements attributed to him in the article lead me to believe that he is at least of average intellegence, maybe even smarter than that. I don't think that Alzheimier's is the cause of senior citizens who fall for sweepstakes scams. I think these cases of pathological gulibilty are unique to the Greatest Generation.
They lived in a time when you could pick up a hitchhiker and not worry about ending up in the trunk of their own car with their own intestines wrapped around their neck. And a time when every war the goverment got involved in was noble, just, and winnable. And the government would take care of them for the rest of their lives.
It explains a lot that this demographic group is the most reliable voting block. Politicians can make any promise to them and never have to keep it.