title: Brain metabolism in substance-induced psychosis and schizophrenia: a preliminary PET study.
abstract: BACKGROUND
  The relation between schizophrenia and cannabis abuse has been widely discussed from etiopathogenetic, psychopathological and neurometabolic points of view. Relatively little has been written about the differences between schizophrenia with co-occurrent cannabis abuse and substance-induced psychotic disorder (SIPD). Given these premises, our study aims to investigate the psychopathological and neurometabolic features of these clinical entities.
  
  
  METHODS
  We enrolled patients experiencing an acute psychotic episode, affected either by schizophrenia with or without cannabis abuse (SCZ +/- CA; n = 5 and n = 5, respectively) with recent onset (<5 years of illness) or by SIPD (n = 6), as diagnosed by the Structured Clinical Interview for DSM-IV Axis I. Patients affected by SIPD were all cannabis abusers. All patients were assessed with the PANSS (Positive and Negative Scale for Schizophrenia), urinary toxicological tests and brain 18-FDG-PET scanning in resting condition. Statistical analysis (ANOVA) was performed with Statistical Parametric Mapping SPM8 and Scenium software.
  
  
  RESULTS
  Bilateral hypermetabolism in the posterior cingulum and the precuneus (p < 0.001) was observed in SIPD patients compared to patients with schizophrenia, with or without cannabis abuse.
  
  
  CONCLUSIONS
  Our preliminary PET findings suggest that substance abuse may cause increased brain metabolism in patients with induced psychosis but not in those with schizophrenia. These differences in brain metabolism were found in the posterior cingulum and precuneus, which are two core regions of the default mode network in humans.
authors.affiliation: Department of Psychiatry, University of Milan, Fondazione IRCCS Cà Granda, Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: Dragogna
authors.forename: Massimo C
authors.initials: MC
authors.lastname: Mauri
authors.forename: Giorgio
authors.initials: G
authors.lastname: Marotta
authors.forename: F Teodora
authors.initials: FT
authors.lastname: Armao
authors.forename: Paolo
authors.initials: P
authors.lastname: Brambilla
authors.forename: A Carlo
authors.initials: AC
authors.lastname: Altamura
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000378:metabolism*; D005260:Female; D006179:Gyrus Cinguli / Q000378:metabolism; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000378:metabolism*; D010296:Parietal Lobe / Q000378:metabolism; D049268:Positron-Emission Tomography; D011605:Psychoses, Substance-Induced / Q000378:metabolism*; D012559:Schizophrenia / Q000378:metabolism*; D055815:Young Adult