Mescaline-induced psychopathological, neuropsychological, and neurometabolic effects in normal subjects: experimental psychosis as a tool for psychiatric research.

Abstract

The psychological, neuropsychological, and neurometabolic effects of the hallucinogenic agent mescaline were investigated in 12 normal men who were volunteers. Mescaline produced an acute psychotic state 3 1/2-4 hr after drug intake, as measured by the Brief Psychiatric Rating Scale (BPRS) and Paranoid Depression Scale (PDS). The Assessment of Altered States of Consciousness (APZ) questionnaire revealed specific effects of mescaline in the visual system. Neuropsychological effects were studied with a face/nonface decision task with known right-hemisphere advantage, in which mescaline induced a decrease of functioning of the right hemisphere. In functional brain imaging using single photon emission computed tomography (SPECT), mescaline produced a "hyperfrontal" pattern with an emphasis on the right hemisphere, which was correlated with mescaline-induced psychotic psychopathology. Our findings question the validity of the concept of hypofrontality as an explanation for schizophrenic symptomatology. The study of psychoactive substances under controlled laboratory conditions has the methodological advantage of intraindividual control, and hence, minimal variability of data.

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 ↕Mixed

  Mescaline produced an acute psychotic state with visual-system effects, right-hemisphere functional decrease, and a hyperfrontal SPECT pattern correlated with psychotic psychopathology.

  Synthesized October 25, 2026

Comparable studies

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