This is Part 1 of a two-part series. Several years prior, Nixon began taking the drug Dilantin for anxiety without consulting a physician.
Doctors say side effects can include dizziness, drowsiness, and change in mental status.
Both revelations about the nation's 37th president were published recently in the book, The Arrogance of Power by Irish journalist Anthony Summers, and each has been confirmed by the people involved. If this was the case, Nixon certainly wasn't the first president unable to perform his duties due to mental or physical impairment, nor was it the first time top advisors saw fit to wield power for an ailing leader. American history is full of examples of incapacitated presidents. And while there is now a constitutional amendment in place to temporarily replace a disabled president against his or her will, it probably will never be invoked, experts say. It is more likely that top advisors would protect a president the way they may have done with Nixon.