The "Bad Trip"—The Etiology of the Adverse LSD Reaction
American Journal of Psychiatry May 1, 1968 J. Thomas Ungerleider, Duke D. Fisher, Marielle Fuller et al. 59 citations
Comparing 25 people hospitalized after taking LSD with 25 regular users who had no reported difficulties, the study found no clear historical or clinical features that could reliably predict who would have an adverse reaction. The authors suggest that LSD interacts with personality traits such as schizoid tendencies and unstable reality testing in a complex manner, making accurate prediction of individual responses nearly impossible.