title: Neurocognitive function and schizophrenia-proneness in individuals dependent on ketamine, on high potency cannabis ('skunk') or on cocaine.
abstract: BACKGROUND
  Ketamine, psychostimulants and cannabis have all been associated with psychotic phenomena but no study has directly compared users of these drugs.
  
  
  OBJECTIVE
  The aim of this study was to assess schizophrenia proneness and neurocognitive function in individuals dependent upon ketamine, cannabis and cocaine.
  
  
  METHODS
  130 volunteers - 29 'skunk' users, 22 cocaine users, 21 ketamine users, along with 28 'recreational' poly-drug users and 30 drug-naïve controls - were assessed on the Schizophrenia Proneness Instrument, Adult version (SPI-A). They were specifically asked to rate symptoms when not under the acute influence of a psychoactive drug.
  
  
  RESULTS
  Ketamine and skunk users manifested the greatest attentional and cognitive disturbances. The symptom profile of the dependent ketamine users was very similar to that of prodromal individuals who transitioned to psychosis.
  
  
  CONCLUSIONS
  Given the recent rapid rise in use of high potency cannabis and of ketamine, these findings are important and clinicians should be careful to rule out the effects of persistent drug use, especially in users of ketamine or skunk, when assessing an individual's risk of psychosis. A longitudinal study is needed to differentiate which basic symptoms persist following abstention from ketamine and skunk.
authors.affiliation: Clinical Psychopharmacology Unit, Research Department of Clinical, Educational and Health Psychology, University College London, London, U.K.
authors.forename: C J A
authors.initials: CJ
authors.lastname: Morgan
authors.forename: S
authors.initials: S
authors.lastname: Duffin
authors.forename: S
authors.initials: S
authors.lastname: Hunt
authors.forename: L
authors.initials: L
authors.lastname: Monaghan
authors.forename: O
authors.initials: O
authors.lastname: Mason
authors.forename: H V
authors.initials: HV
authors.lastname: Curran
mesh_terms: D000293:Adolescent; D000328:Adult; D001288:Attention; D016022:Case-Control Studies; D019970:Cocaine-Related Disorders / Q000150:complications / Q000523:psychology*; D003072:Cognition Disorders / Q000150:complications / Q000523:psychology*; D005260:Female; D006801:Humans; D007649:Ketamine / Q000009:adverse effects*; D008297:Male; D002189:Marijuana Abuse / Q000150:complications / Q000523:psychology*; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D012307:Risk Factors; D012559:Schizophrenia / Q000139:chemically induced*; D057566:Self Report; D019966:Substance-Related Disorders / Q000150:complications / Q000523:psychology*
chemical_list: D007649:Ketamine