title: The effects of cannabis use on salience attribution: a systematic review.
abstract: OBJECTIVE
  The relationship between cannabis use and the onset of psychosis is well established. Aberrant salience processing is widely thought to underpin many of these symptoms. Literature explicitly investigating the relationship between aberrant salience processing and cannabis use is scarce; with those few studies finding that acute tetrahydrocannabinol (THC) administration (the main psychoactive component of cannabis) can result in abnormal salience processing in healthy cohorts, mirroring that observed in psychosis. Nevertheless, the extent of and mechanisms through which cannabis has a modulatory effect on aberrant salience, following both acute and chronic use, remain unclear.
  
  
  METHODS
  Here, we systematically review recent findings on the effects of cannabis use - either through acute THC administration or in chronic users - on brain regions associated with salience processing (through functional MRI data); and performance in cognitive tasks that could be used as either direct or indirect measures of salience processing. We identified 13 studies either directly or indirectly exploring salience processing. Three types of salience were identified and discussed - incentive/motivational, emotional/affective, and attentional salience.
  
  
  RESULTS
  The results demonstrated an impairment of immediate salience processing, following acute THC administration. Amongst the long-term cannabis users, normal salience performance appeared to be underpinned by abnormal neural processes.
  
  
  CONCLUSIONS
  Overall, the lack of research specifically exploring the effects of cannabis use on salience processing, weaken any conclusions drawn. Additional research explicitly focussed on salience processing and cannabis use is required to advance our understanding of the neurocognitive mechanisms underlying the association between cannabis use and development of psychosis.
authors.affiliation: Department of Psychosis Studies,Institute of Psychiatry, Psychology & Neuroscience,King's College London,London,UK.
authors.forename: Surapi Bhairavi
authors.initials: SB
authors.lastname: Wijayendran
authors.affiliation: Department of Psychosis Studies,Institute of Psychiatry, Psychology & Neuroscience,King's College London,London,UK.
authors.forename: Aisling
authors.initials: A
authors.lastname: O'Neill
authors.affiliation: Department of Psychosis Studies,Institute of Psychiatry, Psychology & Neuroscience,King's College London,London,UK.
authors.forename: Sagnik
authors.initials: S
authors.lastname: Bhattacharyya
mesh_terms: D000339:Affect / Q000187:drug effects; D000818:Animals; D001288:Attention / Q000187:drug effects; D001921:Brain / Q000187:drug effects* / Q000502:physiology; D001931:Brain Mapping; D002188:Cannabis / Q000009:adverse effects*; D003071:Cognition / Q000187:drug effects*; D013759:Dronabinol / Q000008:administration & dosage*; D006801:Humans; D008279:Magnetic Resonance Imaging; D009042:Motivation / Q000187:drug effects; D009483:Neuropsychological Tests
chemical_list: D013759:Dronabinol
keywords: cannabis; cognition disorders; functional neuroimaging; marijuana smoking; psychotic disorders