Research library / Observational study

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

Halpern JH, Sherwood AR, Hudson JI, et al. Biological Psychiatry 2005;58(8):624-31

This study asked whether years of religious peyote use cause lasting mental or cognitive harm. Researchers tested three groups of Navajo adults: 61 Native American Church members who regularly take peyote in ceremonies, 36 people recovering from alcohol dependence, and 79 people who used little peyote, alcohol or other drugs. Everyone completed a mental health questionnaire and ten standard tests of memory and attention. The peyote group did no worse than the low-use group on any measure, and heavier lifetime use was not linked to poorer test results. The former drinkers, by contrast, showed clear deficits. The study compares groups at one point in time, so it cannot prove peyote is harmless, and the authors caution that results from structured religious use may not apply to recreational use.