From The Diary of HL Mencken edited by Charles Fecher (NY: Alfred Knopf, 1989), p. 113:

October 12, 1938
Some time ago at a private gathering, Lewis [Dean Lewis (1874-1941) professor of surgery at the Johns Hopkins Medical School and at one time president of the American Medical Association] expressed the opinion that Roosevelt was a paranoiac. Some one present took the news to Washington, and a little while afterward Lewis was visited by an income tax inspector. He was put through a dreadful investigation, greatly to his ire. In the end it turned out that his income tax returns were perfectly in order. The inspector, in fact, apologized for putting him to so much trouble. It seems to me quite plain that this onslaught followed directly out of Lewis’s denunciation of Roosevelt.