In 1967, more than a year after he began using lysergic acid diethylamide (LSD), a 19-year-old U.S. college freshman was admitted to New York’s Presbyterian Hospital complaining of fever and malaise.

LSD was first synthesized by Swiss chemist Albert Hofmann in 1938. He discovered its powerful psychoactive effects in 1943 after accidentally ingesting a small amount and experiencing vivid ...