title: Effect of high-potency cannabis on corpus callosum microstructure.
abstract: BACKGROUND
  The use of cannabis with higher Δ9-tetrahydrocannabinol content has been associated with greater risk, and earlier onset, of psychosis. However, the effect of cannabis potency on brain morphology has never been explored. Here, we investigated whether cannabis potency and pattern of use are associated with changes in corpus callosum (CC) microstructural organization, in patients with first-episode psychosis (FEP) and individuals without psychosis, cannabis users and non-users.
  
  
  METHODS
  The CC of 56 FEP (37 cannabis users) and 43 individuals without psychosis (22 cannabis users) was virtually dissected and segmented using diffusion tensor imaging tractography. The diffusion index of fractional anisotropy, mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity was calculated for each segment.
  
  
  RESULTS
  Across the whole sample, users of high-potency cannabis had higher total CC MD and higher total CC AD than both low-potency users and those who never used (p = 0.005 and p = 0.004, respectively). Daily users also had higher total CC MD and higher total CC AD than both occasional users and those who never used (p = 0.001 and p < 0.001, respectively). However, there was no effect of group (patient/individuals without psychosis) or group x potency interaction for either potency or frequency of use. The within-group analysis showed in fact that the effects of potency and frequency were similar in FEP users and in users without psychosis.
  
  
  CONCLUSIONS
  Frequent use of high-potency cannabis is associated with disturbed callosal microstructural organization in individuals with and without psychosis. Since high-potency preparations are now replacing traditional herbal drugs in many European countries, raising awareness about the risks of high-potency cannabis is crucial.
authors.affiliation: Department of Neurosciences,Mental Health and Sensory Organs,Sapienza University of Rome,Rome,Italy.
authors.forename: S
authors.initials: S
authors.lastname: Rigucci
authors.affiliation: Department of Psychosis Studies,Institute of Psychiatry,Psychology and Neuroscience,King's College London,London,UK.
authors.forename: T R
authors.initials: TR
authors.lastname: Marques
authors.affiliation: Department of Psychosis Studies,Institute of Psychiatry,Psychology and Neuroscience,King's College London,London,UK.
authors.forename: M
authors.initials: M
authors.lastname: Di Forti
authors.affiliation: Department of Psychosis Studies,Institute of Psychiatry,Psychology and Neuroscience,King's College London,London,UK.
authors.forename: H
authors.initials: H
authors.lastname: Taylor
authors.affiliation: Centre for Neuroimaging Sciences,Institute of Psychiatry,Psychology and Neuroscience,King's College London,London,UK.
authors.forename: F
authors.initials: F
authors.lastname: Dell'Acqua
authors.affiliation: Department of Psychological Medicine,Institute of Psychiatry,Psychology and Neuroscience,King's College London,London,UK.
authors.forename: V
authors.initials: V
authors.lastname: Mondelli
authors.affiliation: Department of Psychosis Studies,Institute of Psychiatry,Psychology and Neuroscience,King's College London,London,UK.
authors.forename: S
authors.initials: S
authors.lastname: Bonaccorso
authors.affiliation: Centre for Neuroimaging Sciences,Institute of Psychiatry,Psychology and Neuroscience,King's College London,London,UK.
authors.forename: A
authors.initials: A
authors.lastname: Simmons
authors.affiliation: Department of Psychosis Studies,Institute of Psychiatry,Psychology and Neuroscience,King's College London,London,UK.
authors.forename: A S
authors.initials: AS
authors.lastname: David
authors.affiliation: Department of Neurosciences,Mental Health and Sensory Organs,Sapienza University of Rome,Rome,Italy.
authors.forename: P
authors.initials: P
authors.lastname: Girardi
authors.affiliation: Department of Psychological Medicine,Institute of Psychiatry,Psychology and Neuroscience,King's College London,London,UK.
authors.forename: C M
authors.initials: CM
authors.lastname: Pariante
authors.affiliation: Department of Psychosis Studies,Institute of Psychiatry,Psychology and Neuroscience,King's College London,London,UK.
authors.forename: R M
authors.initials: RM
authors.lastname: Murray
authors.affiliation: Department of Psychosis Studies,Institute of Psychiatry,Psychology and Neuroscience,King's College London,London,UK.
authors.forename: P
authors.initials: P
authors.lastname: Dazzan
mesh_terms: D000293:Adolescent; D000328:Adult; D000341:Affective Disorders, Psychotic / Q000000981:diagnostic imaging* / Q000453:epidemiology; D016880:Anisotropy; D002188:Cannabis; D016022:Case-Control Studies; D015897:Comorbidity; D003337:Corpus Callosum / Q000000981:diagnostic imaging*; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008385:Marijuana Smoking / Q000453:epidemiology*; D011618:Psychotic Disorders / Q000000981:diagnostic imaging* / Q000453:epidemiology; D012559:Schizophrenia / Q000000981:diagnostic imaging* / Q000453:epidemiology; D055815:Young Adult
keywords: Cannabis; corpus callosum; first-episode psychosis; tractography; white matter