title: Chronic effects of cannabis use on the auditory mismatch negativity.
abstract: BACKGROUND
  Cannabis use is associated with the development of psychotic symptoms and increased risk for schizophrenia. The mismatch negativity (MMN) is a brain event-related potential marker of change detection thought to index glutamatergic N-methyl-D-aspartate receptor-mediated neurotransmission, which is known to be deficient in schizophrenia. This study examined auditory MMN in otherwise healthy chronic cannabis users compared with nonuser control subjects.
  
  
  METHODS
  Forty-two chronic cannabis users and 44 nonuser healthy control subjects completed a multi-feature MMN paradigm, which included duration, frequency, and intensity deviants (deviants 6%; standards 82%). The MMN was compared between users and control subjects as well as between long- and short-term users and age- and gender-matched control subjects. Associations between MMN, cannabis use measures, and symptoms were examined.
  
  
  RESULTS
  The MMN amplitude was significantly reduced to frequency but not duration or intensity deviants in overall cannabis users relative to control subjects. Frequency MMN was similarly attenuated in short- and long-term users relative to control subjects. Long-term users also exhibited reduced duration MMN relative to control subjects and short-term users and this was correlated with increased duration of exposure to cannabis and increased psychotic-like experiences during intoxication. In short-term users, a younger age of onset of regular cannabis use and greater frequency of use were associated with greater psychotic-like experiences and symptomatic distress.
  
  
  CONCLUSIONS
  These results suggest impaired sensory memory that might reflect N-methyl-D-aspartate receptor dysfunction in chronic cannabis users. The pattern of MMN alterations in cannabis users differed from that typically observed in patients with schizophrenia, indicating overlapping but distinct underlying pathology.
authors.affiliation: School of Psychology and ψ-P3: Centre for Psychophysics, Psychophysiology and Psychopharmacology, University of Wollongong, Wollongong.
authors.forename: Lisa-Marie
authors.initials: LM
authors.lastname: Greenwood
authors.affiliation: School of Psychology and ψ-P3: Centre for Psychophysics, Psychophysiology and Psychopharmacology, University of Wollongong, Wollongong.
authors.forename: Samantha J
authors.initials: SJ
authors.lastname: Broyd
authors.affiliation: School of Psychology and ψ-P3: Centre for Psychophysics, Psychophysiology and Psychopharmacology, University of Wollongong, Wollongong.
authors.forename: Rodney
authors.initials: R
authors.lastname: Croft
authors.affiliation: School of Psychology and Priority Research Centre for Translational Neuroscience and Mental Health, University of Newcastle, Newcastle; Schizophrenia Research Institute, Sydney, New South Wales, Australia.
authors.forename: Juanita
authors.initials: J
authors.lastname: Todd
authors.affiliation: School of Psychology and Priority Research Centre for Translational Neuroscience and Mental Health, University of Newcastle, Newcastle; Schizophrenia Research Institute, Sydney, New South Wales, Australia.
authors.forename: Patricia T
authors.initials: PT
authors.lastname: Michie
authors.affiliation: School of Psychology and ψ-P3: Centre for Psychophysics, Psychophysiology and Psychopharmacology, University of Wollongong, Wollongong.
authors.forename: Stuart
authors.initials: S
authors.lastname: Johnstone
authors.affiliation: Institute of Psychiatry, Kings College, London, United Kingdom.
authors.forename: Robin
authors.initials: R
authors.lastname: Murray
authors.affiliation: School of Psychology and ψ-P3: Centre for Psychophysics, Psychophysiology and Psychopharmacology, University of Wollongong, Wollongong; Schizophrenia Research Institute, Sydney, New South Wales, Australia. Electronic address: nadia@uow.edu.au.
authors.forename: Nadia
authors.initials: N
authors.lastname: Solowij
mesh_terms: D000293:Adolescent; D000328:Adult; D002188:Cannabis / Q000009:adverse effects*; D016022:Case-Control Studies; D002908:Chronic Disease; D005072:Evoked Potentials, Auditory / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000378:metabolism / Q000503:physiopathology*; D008875:Middle Aged; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D012559:Schizophrenia / Q000378:metabolism / Q000503:physiopathology; D063189:Symptom Assessment; D009435:Synaptic Transmission / Q000187:drug effects; D013997:Time Factors; D055815:Young Adult
chemical_list: D016194:Receptors, N-Methyl-D-Aspartate
keywords: Cannabis; MMN; event-related potentials; mismatch negativity; schizophrenia; sensory memory