Ronald Reagan's son suggests in a new book that his father suffered from the beginning stages of Alzheimer's disease while he was still in the White House.

U.S. News and amp; World Report quotes excerpts from Ron Reagan's book "My Father at 100: A Memoir" in which Reagan's son says he believes his father would have left office had the disease been diagnosed then.

The younger Reagan recalls how his father became uncharacteristically lost for words and looked "bewildered" during the 1984 presidential debates. He says his father may have suspected Alzheimer's in 1986 when he was flying over familiar canyons north of Los Angeles and could no longer remember their names.

White House doctors have said they saw no evidence of the disease while he was president. He was diagnosed in 1994, five years after leaving office.