title: An experimental study of catechol-o-methyltransferase Val158Met moderation of delta-9-tetrahydrocannabinol-induced effects on psychosis and cognition.
abstract: Observational studies have suggested that psychometric psychosis liability and a functional polymorphism in the catechol-O-methyltransferase (COMT Val(158)Met) gene moderate the psychosis-inducing effect of cannabis. To replicate and extend this finding, a double-blind, placebo-controlled cross-over design was used in which patients with a psychotic disorder (n=30), relatives of patients with a psychotic disorder (n=12), and healthy controls (n=32) were exposed to Delta-9-tetrahydrocannabinol (Delta-9-THC, the principal component of cannabis) or placebo, followed by cognitive assessment and assessment of current psychotic experiences. Previous expression of psychometric psychosis liability was also assessed. Models of current psychotic experiences and cognition were examined with multilevel random regression analyses to assess (i) main effects of genotype and condition, (ii) interactions between condition and genotype, and (iii) three-way interactions between condition, genotype, and psychometric psychosis liability. Carriers of the Val allele were most sensitive to Delta-9-THC-induced psychotic experiences, but this was conditional on prior evidence of psychometric psychosis liability. Delta-9-THC impacted negatively on cognitive measures. Carriers of the Val allele were also more sensitive to Delta-9-THC-induced memory and attention impairments compared to carriers of the Met allele. Experimental effects of Delta-9-THC on cognition and psychosis are moderated by COMT Val(158)Met genotype, but the effects may in part be conditional on the additional presence of pre-existing psychosis liability. The association between cannabis and psychosis may represent higher order gene-environment and gene-gene interactions.
authors.affiliation: Department of Psychiatry and Neuropsychology, South Limburg Mental Health Research and Teaching Network, EURON, Maastricht University, Maastricht, The Netherlands.
authors.forename: Cécile
authors.initials: C
authors.lastname: Henquet
authors.forename: Araceli
authors.initials: A
authors.lastname: Rosa
authors.forename: Lydia
authors.initials: L
authors.lastname: Krabbendam
authors.forename: Sergi
authors.initials: S
authors.lastname: Papiol
authors.forename: Lourdes
authors.initials: L
authors.lastname: Fananás
authors.forename: Marjan
authors.initials: M
authors.lastname: Drukker
authors.forename: Johannes G
authors.initials: JG
authors.lastname: Ramaekers
authors.forename: Jim
authors.initials: J
authors.lastname: van Os
mesh_terms: D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence / Q000235:genetics; D019943:Amino Acid Substitution / Q000235:genetics; D001921:Brain / Q000187:drug effects / Q000201:enzymology / Q000503:physiopathology; D002394:Catechol O-Methyltransferase / Q000235:genetics* / Q000378:metabolism; D003072:Cognition Disorders / Q000139:chemically induced / Q000201:enzymology / Q000235:genetics; D018592:Cross-Over Studies; D004252:DNA Mutational Analysis; D004298:Dopamine / Q000378:metabolism; D004311:Double-Blind Method; D013759:Dronabinol / Q000009:adverse effects*; D004781:Environmental Exposure; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005820:Genetic Testing; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D010919:Placebos; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D011605:Psychoses, Substance-Induced / Q000201:enzymology* / Q000235:genetics* / Q000503:physiopathology; D011618:Psychotic Disorders / Q000201:enzymology / Q000235:genetics / Q000503:physiopathology
chemical_list: D010919:Placebos; D013759:Dronabinol; D002394:Catechol O-Methyltransferase; D004298:Dopamine