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

Abstract

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. 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. 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. 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.

In the evidence

This study is part of the evidence base for a synthesis in the library. Here is how each one recorded it.

• State of the evidence: Mescaline →No effect

  Regular ceremonial peyote use showed no significant psychological or cognitive deficits, and lifetime peyote use was not associated with neuropsychological performance.

  Synthesized October 25, 2026

Comparable studies

Other observational and cohort studies on mescaline, most cited first.