title: Parietal lobe volume deficits in adolescents with schizophrenia and adolescents with cannabis use disorders.
abstract: OBJECTIVE
  In early-onset schizophrenia (EOS), the earliest structural brain volumetric abnormalities appear in the parietal cortices. Early exposure to cannabis may represent an environmental risk factor for developing schizophrenia. This study characterized cerebral cortical gray matter structure in adolescents in regions of interest (ROIs) that have been implicated in EOS and cannabis use disorders (CUD).
  
  
  METHODS
  T1-weighted magnetic resonance images were acquired from adolescents with EOS (n = 35), CUD (n = 16), EOS + CUD (n = 13), and healthy controls (HC) (n = 51). Using FreeSurfer, brain volume was examined within frontal, temporal, parietal and subcortical ROIs by a 2 (EOS versus no EOS) × 2 (CUD versus no CUD) design using multivariate analysis of covariance. In ROIs in which volumetric differences were identified, additional analyses of cortical thickness and surface area were conducted.
  
  
  RESULTS
  A significant EOS-by-CUD interaction was observed. In the left superior parietal region, both "pure" EOS and "pure" CUD had smaller gray matter volumes that were associated with lower surface area compared with HC. A similar alteration was observed in the comorbid group compared with HC, but there was no additive volumetric deficit found in the comorbid group compared with the separate groups. In the left thalamus, the comorbid group had smaller gray matter volumes compared with the CUD and HC groups.
  
  
  CONCLUSIONS
  These preliminary data indicate that the presence of a CUD may moderate the relationship between EOS and cerebral cortical gray matter structure in the left superior parietal lobe. Future research will follow this cohort over adolescence to further examine the impact of cannabis use on neurodevelopment.
authors.affiliation: University of Minnesota, USA. kumra002@umn.edu
authors.forename: Sanjiv
authors.initials: S
authors.lastname: Kumra
authors.forename: Paul
authors.initials: P
authors.lastname: Robinson
authors.forename: Rabindra
authors.initials: R
authors.lastname: Tambyraja
authors.forename: Daniel
authors.initials: D
authors.lastname: Jensen
authors.forename: Caroline
authors.initials: C
authors.lastname: Schimunek
authors.forename: Alaa
authors.initials: A
authors.lastname: Houri
authors.forename: Tiffany
authors.initials: T
authors.lastname: Reis
authors.forename: Kelvin
authors.initials: K
authors.lastname: Lim
mesh_terms: D000293:Adolescent; D002540:Cerebral Cortex / Q000473:pathology / Q000503:physiopathology; D015897:Comorbidity; D004292:Dominance, Cerebral / Q000502:physiology; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D002189:Marijuana Abuse / Q000175:diagnosis* / Q000503:physiopathology; D015999:Multivariate Analysis; D009929:Organ Size / Q000502:physiology; D010296:Parietal Lobe / Q000473:pathology* / Q000503:physiopathology; D012016:Reference Values; D012307:Risk Factors; D012559:Schizophrenia / Q000175:diagnosis* / Q000503:physiopathology; D013223:Statistics as Topic; D013788:Thalamus / Q000473:pathology / Q000503:physiopathology