RELAPSE OF PARANOID PSYCHOTIC STATE IN METHAMPHETAMINE MODEL OF SCHIZOPHRENIA

The study of the clinical course of methamphetamine (MAP) psychosis yields insights into the biological aspect of the relapse of the paranoid psychotic state with hallucination in schizophrenia. A series of MAP psychosis studies in Japan conducted over a period of more than four decades revealed three types of clinical courses of MAP psychosis after discontinuation of MAP: transient type, prolonged type, and persistent type. Identification of the latter two indicates a lasting change in the brain that produces and maintains a schizophrenia-like paranoid psychotic state without MAP. The characteristic course seen in the transient type is acute recurrence of the psychotic state after a long remission period, almost identical to the initial episode, due to reuse of MAP or to psychological stressors. Such lasting vulnerability of the brain to schizophrenia-like psychotic symptoms may be caused by a lasting sensitization of the brain to the psychotogenic action of MAP resulting from its chronic abuse. Experimental studies using animals sensitized to MAP-induced stereotype suggest that lasting enhancement of MAP-induced dopamine release in the striatum and nucleus accumbens is related to the development and expression of brain vulnerability to schizophrenic symptoms.