title: Hemispheric language asymmetry in first episode psychosis and schizotypy: the role of cannabis consumption and cognitive disorganization.
abstract: Cannabis use has been related to an elevated psychosis risk and attenuated cognitive functioning. Cannabis-related cognitive impairments are also observed in populations along the psychosis dimension. We here investigated whether a potential behavioral marker of the psychosis dimension (attenuated functional hemispheric asymmetry) is even further attenuated in individuals using cannabis (CU) vs those not using cannabis (nCU). We tested 29 patients with first-episode psychosis (FEP; 11 CU) and 90 healthy controls (38 CU) on lateralized lexical decisions assessing left-hemisphere language dominance. In patients, psychotic symptoms were assessed by Positive & Negative Symptom Scale (PANSS). In controls, self-reported schizotypy was assessed (The Oxford-Liverpool Inventory of Feelings and Experiences: O-LIFE). Results indicated that nCU FEP patients had a relative reduced hemispheric asymmetry, as did controls with increasing cognitive disorganization (CogDis) scores, in particular when belonging to the group of nCU controls. Positive, disorganized and negative PANSS scores in patients and negative and positive schizotypy in controls were unrelated to hemispheric asymmetry. These findings suggest that cannabis use potentially balances rather than exacerbates uncommon hemispheric laterality patterns. Moreover, in healthy populations, the potential stabilization of typical hemispheric asymmetry in CU might be most relevant to individuals with elevated CogDis. We discuss the potential beneficial and harmful effects of cannabis use along the psychosis dimension together with propositions for future studies that should account for the mediating role of additional substances (eg nicotine), cannabis composition (eg cannabidiol content), and individual differences (eg physical health, or absence of significant polysubstance use).
authors.affiliation: Clienia AG Littenheid, 9573 Sirnach, CH, Switzerland; Department of Experimental Psychology; Daniela.herzig@clienia.ch.
authors.forename: Daniela A
authors.initials: DA
authors.lastname: Herzig
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, UK;
authors.forename: Sarah
authors.initials: S
authors.lastname: Sullivan
authors.affiliation: Department of Mental Health, University College London, London, UK;
authors.forename: Glyn
authors.initials: G
authors.lastname: Lewis
authors.affiliation: Institute of Psychology, Health, and Society, University of Liverpool, Liverpool, UK;
authors.forename: Rhiannon
authors.initials: R
authors.lastname: Corcoran
authors.affiliation: Psychiatry Research Group, School of Community Based Medicine, University of Manchester, Manchester, UK;
authors.forename: Richard
authors.initials: R
authors.lastname: Drake
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, UK;
authors.forename: Jonathan
authors.initials: J
authors.lastname: Evans
authors.affiliation: Neuropsychopharmacology Unit, Imperial College London, London, UK;
authors.forename: David
authors.initials: D
authors.lastname: Nutt
authors.affiliation: Department of Experimental Psychology; Faculty of Social Science and Politics, University of Lausanne, CH, Lausanne, Switzerland.
authors.forename: Christine
authors.initials: C
authors.lastname: Mohr
mesh_terms: D000328:Adult; D002188:Cannabis; D005260:Female; D007839:Functional Laterality / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007802:Language; D008297:Male; D011618:Psychotic Disorders / Q000188:drug therapy / Q000503:physiopathology*; D012569:Schizotypal Personality Disorder / Q000188:drug therapy / Q000503:physiopathology*; D055815:Young Adult
keywords: cannabis; cognition; drugs; laterality; psychosis-proneness; schizotypy