What Can We Learn About Schizophrenia From Studying the Human Model, Drug-Induced

When drug-induced psychoses were first identified in the mid-20th century, schizophrenia was considered a discrete diseasewithalikelygeneticcause.Consequently,drug-inducedpsycho-seswerenotconsideredcentraltounderstandingschizophreniaastheywerethoughttobephenocopiesratherthanexamplesoftheillnesssecondarytoaparticularknowncause.However,nowthat we know that schizophrenia is a clinical syndrome withmultiplecomponentcauses,thenitisclearthatthedrug-inducedpsychoses have much to teach us. This article shows how themajor neuropharmacological theories of schizophrenia havetheiroriginsinstudiesofthe effects ofdrugs ofabuse.ResearchintotheeffectsofLSDinitiatedtheserotonergicmodel;amphet-amines the dopamine hypothesis, PCP and ketamine the gluta-matergic hypothesis, whilemost recently the effectsof cannabishave provoked interest in the role of endocannabinoids inschizophrenia. None of these models account for the completepicture of schizophrenia; rather the various drug models mimicdifferentaspectsoftheillness.Determiningthedifferentmolec-ulareffectsofthosedrugswhosepharmacologicaleffectsdoanddo not mimic the various aspects of schizophrenia has much toteach us concerning the pathogenesis of the illness.