American Board of Psychiatry and Neurology (ABPN) Practice Exam 2026 - Free ABPN Practice Questions and Study Guide

Phencyclidine (PCP) primarily exerts its hallucinogenic effects through NMDA antagonism. NMDA (N-methyl-D-aspartate) receptors are a subtype of glutamate receptors that play a crucial role in synaptic plasticity and memory function. By blocking these receptors, PCP disrupts normal glutamate signaling in the brain, which can lead to alterations in perception, mood, and cognition, characteristic of hallucinogenic experiences.

This mechanism is particularly significant as it contributes to the dissociative effects of PCP, distinguishing it from other hallucinogens that may act primarily on serotonin pathways or dopamine systems. The NMDA receptor blockade is believed to be responsible for not just the hallucinogenic effects but also other severe symptoms like agitation and dissociation that can occur with PCP use.

Understanding the specific action of PCP on NMDA receptors helps to clarify why interventions for PCP intoxication focus on supportive care and managing the psychological effects rather than targeting neurotransmitter systems unrelated to the primary mechanism of action.