Predicting Long-term Psychedelic Side-effects

Psychedelic drugs are seeing a surge of interest from mainstream medicine, and initial results suggest that psychedelic-therapy can be a safe and effective treatment for some mental health conditions. However, the side-effect profile is still incompletely understood. In particular, the use of psychedelics has been posited to carry a risk of triggering latent psychotic disorders or persistent visual hallucination, known as Hallucinogen Persisting Perception Disorder (HPPD). In order to better understand the prevalence and risk factors of such side-effects, Katie Zhou and colleagues surveyed 654 people online who were planning to take psychedelics through their own initiative. Of those, 315 people were resurveyed two weeks after their experience and 212 people were resurveyed again four weeks after their experience. The sample was 74% male, and 77% university educated. About one third had been diagnosed with at least one psychiatric condition. The authors found a weak correlation between lifetime psychedelic use and both delusional ideation and magical thinking. However, on average, delusional ideation was slightly reduced one month after psychedelic use. These results suggest that schizotypal traits may not be caused by taking LSD or magic mushrooms, in keeping with the principle that correlation does not imply causation. About a third of individuals surveyed at the four-week mark did have some lingering hallucinatory sensory experiences, such as intensified colors and afterimages. However, the majority of those who experienced this did not report being distressed by it. The strongest predictors of persistent visual aftereffects were the personality trait absorption—the tendency to be easily immersed in sensory or imaginative experiences—and younger age. This corroborates previous findings showing that young people and adolescents may be at a particular risk of HPPD. According to the authors, empirical scrutiny of the potential risks of psychedelics should accompany changes in policy and access to psychedelic drugs.