title: A systematic review of the effect of cannabidiol on cognitive function: Relevance to schizophrenia.
abstract: Cognitive impairment is a core symptom domain of schizophrenia, neurological disorders and substance abuse. It is characterised by deficits in learning, memory, attention and executive functioning and can severely impact daily living. Antipsychotic drugs prescribed to treat schizophrenia provide limited cognitive benefits and novel therapeutic targets are required. Cannabidiol (CBD), a component of the cannabis plant, has anti-inflammatory and antipsychotic-like properties; however, its ability to improve cognitive impairment has not been thoroughly explored. The aim of this systematic review was to evaluate preclinical and clinical literature on the effects of CBD in cognitive domains relevant to schizophrenia.
  
  
  
  A systematic literature search was performed across numerous electronic databases for English language articles (January 1990-March 2016), with 27 articles (18 preclinical and 9 clinical studies) included in the present review.
  
  
  
  CBD improves cognition in multiple preclinical models of cognitive impairment, including models of neuropsychiatric (schizophrenia), neurodegenerative (Alzheimer's disease), neuro-inflammatory (meningitis, sepsis and cerebral malaria) and neurological disorders (hepatic encephalopathy and brain ischemia). To date, there is one clinical investigation into the effects of CBD on cognition in schizophrenia patients, with negative results for the Stroop test. CBD attenuates Δ9-THC-induced cognitive deficits.
  
  
  
  The efficacy of CBD to improve cognition in schizophrenia cannot be elucidated due to lack of clinical evidence; however, given the ability of CBD to restore cognition in multiple studies of impairment, further investigation into its efficacy in schizophrenia is warranted. Potential mechanisms underlying the efficacy of CBD to improve cognition are discussed.
authors.affiliation: Centre for Translational Neuroscience, Illawarra Health and Medical Research Institute, University of Wollongong, 2522, NSW, Australia; Illawarra Health and Medical Research Institute, University of Wollongong, 2522, NSW, Australia; Centre for Medical and Molecular Biosciences, Faculty of Science, Medicine and Health, University of Wollongong, 2522, NSW, Australia.
authors.forename: Ashleigh L
authors.initials: AL
authors.lastname: Osborne
authors.affiliation: School of Psychology, Faculty of Social Sciences, University of Wollongong, 2522, NSW, Australia; Illawarra Health and Medical Research Institute, University of Wollongong, 2522, NSW, Australia.
authors.forename: Nadia
authors.initials: N
authors.lastname: Solowij
authors.affiliation: Centre for Translational Neuroscience, Illawarra Health and Medical Research Institute, University of Wollongong, 2522, NSW, Australia; Illawarra Health and Medical Research Institute, University of Wollongong, 2522, NSW, Australia; Centre for Medical and Molecular Biosciences, Faculty of Science, Medicine and Health, University of Wollongong, 2522, NSW, Australia. Electronic address: katrina_green@uow.edu.au.
authors.forename: Katrina
authors.initials: K
authors.lastname: Weston-Green
mesh_terms: D014150:Antipsychotic Agents; D002185:Cannabidiol; D003071:Cognition; D013759:Dronabinol; D006801:Humans; D012559:Schizophrenia
chemical_list: D014150:Antipsychotic Agents; D002185:Cannabidiol; D013759:Dronabinol
keywords: Alzheimer’s disease; Antipsychotic drugs; Brain ischemia; Cannabidiol; Cannabis; Cerebral malaria; Cognition; Cognitive impairment; Cognitive testing; Hepatic encephalopathy; Meningitis; Neuro-inflammation; Neurodegeneration; Neuropsychiatric; Schizophrenia; Sepsis; Δ9-Tetrahydrocannabinol