Study Finds No Psychological or Cognitive Deficits among Native Americans Who Use Peyote Regularly in Religious Settings

November 04, 2005

Cindy Lepore
Public Affairs

Belmont, MA - Native Americans who use the hallucinogen peyote regularly in connection with religious ceremonies show no evidence of brain damage or psychological problems, report researchers at Harvard-affiliated McLean Hospital.

Dr. John Halpern

Dr. John Halpern with Shiprock in the background.
(click to enlarge)

In fact, members of the Navajo tribe who regularly use peyote actually scored significantly better on several measures of overall mental health than did subjects from the same tribe who were not members of the religious group and did not use the hallucinogen, according to a paper published in the Nov. 4 issue (PubMed) of Biological Psychiatry.

"We found no evidence that these Native Americans had residual neurocognitive problems. Despite lifelong participation in the peyote church, they performed just as well on mental tests as those who had never used peyote,'' said the study's first author John Halpern, MD, of McLean Hospital's Biological Psychiatry Laboratory. The study was funded, in part, by the National Institute on Drug Abuse.

Teepee at sunset.

A teepee at sunset set up for a Peyote Ceremony.
(click to enlarge)

Beyond that, the peyote users scored better on several measures of the Rand Mental Health Inventory (RMHI), a test used to diagnose psychological problems and determine overall mental health, he said. Among the RMHI scales are measures of anxiety, depression, loss of behavioral or emotional control, and psychological distress. Halpern emphasized that the better scores among peyote users were not necessarily attributable to the use of peyote itself, but more likely due to the social and psychological benefits of being members of the Native American Church community.

The study, which took five years to complete, looked at 61 members of the Native American Church (NAC), who regularly used the hallucinogenic cactus and had each ingested it at least 100 times as part of their religion. They were compared on a battery of tests with 79 Navajos who reported minimal use of peyote, and 36 tribe members who had past problems with alcohol but who were now sober.

The former alcohol users scored significantly worse, compared to the other two groups, on every scale of the mental health test and on two tests that looked at memory.

Peyote cactus.

A drawing of the peyote cactus.
(click to enlarge)

"Within the peyote group, total lifetime peyote use was not significantly associated with neuropsychological performance," concluded the paper. "We found no evidence of psychological or cognitive deficits among Native Americans using peyote regularly in a religious setting.''

The paper warned, however, that the conclusions should not be generalized to those who use hallucinogenic drugs in illicit settings. There are 300,000 Native Americans who regularly use peyote as a religious sacrament and are allowed to do so by law.

"This study applies only to Native Americans in this church," said Harrison G. Pope, Jr., MD, director of McLean's Biological Psychiatry Laboratory and senior author of the study. "From our data, we cannot say what the effects of peyote might be in any other group."

McLean Hospital, consistently ranked the nation's top psychiatric hospital by U.S. News & World Report, is an affiliate of Harvard Medical School and Massachusetts General Hospital and a member of Partners HealthCare.

Email this page