title: Delayed preattentional functioning in early psychosis patients with cannabis use.
abstract: BACKGROUND
  Cannabis use is prevalent among the early psychosis (EP) population. The event-related potentials, mismatch negativity (MMN) and P3a are reduced in EP. Cannabinoids have been shown to modulate N-methyl-D-aspartate receptors which are involved in MMN generation.
  
  
  OBJECTIVE
  This study is the first to investigate the effects of cannabis use on MMN/P3a in EP.
  
  
  METHODS
  EP was defined as a history of psychosis or psychotic symptoms with no progression to date to chronic schizophrenia. Twenty-two EP patients with cannabis use (EP + CANN), 22 non-cannabis-using EP patients (EP-CANN) and 21 healthy controls participated in this study. MMN/P3a was elicited using a two-tone, auditory paradigm with 8% duration deviants.
  
  
  RESULTS
  As expected, EP-CANN showed marked reductions in MMN/P3a amplitudes compared to controls. However, EP + CANN showed evidence of a different pattern of neurophysiological expression of MMN/P3a compared to non-using patients, most notably in terms of delayed frontal MMN/P3a latencies.
  
  
  CONCLUSIONS
  This study provides further evidence that MMN/P3a deficits are present during early psychosis and suggests that this biomarker may have utility in differentiating substance- from non-substance-related psychoses.
authors.affiliation: School of Psychology, University of Wollongong, Wollongong, NSW, 2522, Australia. nicole.pesa@sydney.edu.au
authors.forename: Nicole
authors.initials: N
authors.lastname: Pesa
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Hermens
authors.forename: Robert A
authors.initials: RA
authors.lastname: Battisti
authors.forename: Manreena
authors.initials: M
authors.lastname: Kaur
authors.forename: Ian B
authors.initials: IB
authors.lastname: Hickie
authors.forename: Nadia
authors.initials: N
authors.lastname: Solowij
mesh_terms: D000328:Adult; D001288:Attention; D003071:Cognition; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000503:physiopathology / Q000523:psychology*; D011618:Psychotic Disorders / Q000503:physiopathology / Q000523:psychology*