According to Summers’s account, Nixon started taking Dilantin after Dreyfus gave him the drug soon after the 1968 election. The drug is used principally for the treatment of epilepsy, but Dreyfus, who is not a doctor, advocated the use of the drug for mood disorders such as depression.

Nixon apparently told Dreyfus he wanted “some of that,” and Dreyfus agreed to give the drug to his friend without a prescription, Summers writes. One of the side effects of the drug is that it can cause “severe mental confusion.”