Psychological and cognitive effects of long-term peyote use among Native Americans

Biol Psychiatry. 2005 Oct 15;58(8):624-31. doi: 10.1016/j.biopsych.2005.06.038.


Background: Hallucinogens are widely used, both by drug abusers and by peoples of traditional cultures who ingest these substances for religious or healing purposes. However, the long-term residual psychological and cognitive effects of hallucinogens remain poorly understood.

Methods: We recruited three groups of Navajo Native Americans, age 18-45: 1) 61 Native American Church members who regularly ingested peyote, a hallucinogen-containing cactus; 2) 36 individuals with past alcohol dependence, but currently sober at least 2 months; and 3) 79 individuals reporting minimal use of peyote, alcohol, or other substances. We administered a screening interview, the Rand Mental Health Inventory (RMHI), and ten standard neuropsychological tests of memory and attentional/executive functions.

Results: Compared to Navajos with minimal substance use, the peyote group showed no significant deficits on the RMHI or any neuropsychological measures, whereas the former alcoholic group showed significant deficits (p < .05) on every scale of the RMHI and on two neuropsychological measures. Within the peyote group, total lifetime peyote use was not significantly associated with neuropsychological performance.

Conclusions: We found no evidence of psychological or cognitive deficits among Native Americans using peyote regularly in a religious setting. It should be recognized, however, that these findings may not generalize to illicit hallucinogen users.

Publication types

  • Clinical Trial
  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Attention / drug effects*
  • Attention / physiology
  • Cognition / drug effects*
  • Cognition / physiology
  • Demography
  • Female
  • Hallucinogens / administration & dosage*
  • Humans
  • Indians, North American*
  • Interviews as Topic
  • Male
  • Memory / drug effects
  • Mescaline / administration & dosage*
  • Middle Aged
  • Neuropsychological Tests
  • Personality Inventory / statistics & numerical data
  • Problem Solving / drug effects
  • Time


  • Hallucinogens
  • Mescaline