People have speculated about how far Ronald Reagan's Alzheimer's went back since his diagnosis in 1994, but his own son now says that the former president began showing signs of the degenerative disease while in the Oval Office. In My Father at 100, Ron Reagan writes that while watching his father debate Walter Mondale in 1984, "My heart sank as he floundered his way through his responses, fumbling with notes, uncharacteristically lost for words. He looked tired and bewildered," the Washington Post reports.
Two years later, in 1986, the president "might have suspected that all was not as it should be," when he couldn't summon the names of California canyons while flying over them. In 1989, doctors operating on Reagan's brain “detected what they took to be probable signs of Alzheimer’s," though no definitive diagnosis was given. But while the younger Reagan finds "no evidence that my father (or anyone else) was aware of his medical condition while he was in office,” he wonders: “Had the diagnosis been made in, say, 1987, would he have stepped down? I believe he would have.” (Read more Ronald Reagan stories.)