In 1962 Sidney Cohen presented the medical community with its first warning about the dangers of the drug LSD. LSD had arrived in the United States in 1949 and was originally perceived as a psychotomimetic capable of producing a model psychosis. But in the mid 1950s intellectuals in Southern California redefined LSD as a psychedelic capable of producing mystical enlightenment. Though LSD was an investigational drug, authorized only for experimental use, by the late 1950s psychiatrists and psychologists were administering it to cure neuroses and alcoholism and to enhance creativity. Cohen's 1960 study of LSD effects concluded that the drug was safe if given in a supervised medical setting, but by 1962 his concern about popularization, nonmedical use, black market LSD, and patients harmed by the drug led him to warn that the spread of LSD was dangerous. The subsequent government crackdown and regulation of LSD preceded the 1960s drug movement and was prompted by medical, not social, concerns.