Ronald Reagan may have shown signs of Alzheimer’s as early as the 1984 election, says his son in his new memoir, My Father at 100, to be published by Viking. Ron Reagan remembers that, in the mid-1980s, Reagan struggled with his memory, and looked "lost and bewildered" during his debates with Walter Mondale. He became alarmed when he flew over familiar canyons near Los Angeles and couldn't remember their names. But Reagan is quick to add that his speculation doesn't undermine his father's legacy: "Does this delegitimize his presidency? Only to the extent that President Kennedy's Addison's disease or Lincoln's clinical depression undermine theirs." And had Reagan been diagnosed, his son believes he would have left office before the end of his second term in 1989. Reagan died in 2004 of complications from the disease.