It's scary to think that a standing president could be suffering from Alzheimer's, but Ronald Reagan's son suggests that his father might have been in the beginning stages during his presidency.  In his new book, Ron Reagan writes that he believes his father would have left office before his second term ended in 1989, had the disease been diagnosed then.  Reagan was diagnosed in 1994, five years after leaving the Oval Office., and died in 2004 at the age of 93.