title: Cortical thinness and volume differences associated with marijuana abuse in emerging adults.
abstract: BACKGROUND
  The prevalence of marijuana (MJ) use among youth and its legalization for medical or recreational use has intensified public health endeavors of understanding MJ effects on brain structure and function. Studies indicate that MJ use is related to impaired cognitive performance, and altered functional brain activation and chemistry in adolescents and adults, but MJ effects on brain morphology in emerging adults are less understood.
  
  
  METHODS
  Fifteen MJ users (age 21.8±3.6, 2 females) and 15 non-user (NU) participants (age 22.3±3.5, 2 females) were included, demographically matched on age, education and alcohol use. High-resolution structural MR images were acquired at 3Tesla. Cortical thickness (CT) and volumetric analyses were performed using Freesurfer. A priori regions of interest (ROI) included orbitofrontal and cingulate cortices, amygdala, hippocampus and thalamus.
  
  
  RESULTS
  Whole brain CT analysis did not result in significant group differences in a priori ROIs but revealed MJ users had significantly less CT (i.e., thinness) in right fusiform gyrus (rFG) compared to NU (p<0.05). Thalamic volume was significantly smaller in MJ users compared to NU (right, p=0.05; left, p=0.01) and associated with greater non-planning (p<0.01) and overall impulsivity (p=0.04). There were no other group differences.
  
  
  CONCLUSIONS
  RFG cortical thinness and smaller thalamic volume in emerging adults is associated with MJ abuse. Furthermore, smaller thalamic volume associated with greater impulsivity contributes to growing evidence that the thalamus is neurobiologically perturbed by MJ use. Collectively, altered thalamic and rFG structural integrity may interfere with their known roles in regulating visuoperceptual and object information processing.
authors.affiliation: Behavioral Psychopharmacology Research Laboratory, McLean Hospital, Belmont, MA, USA; McLean Imaging Center, McLean Hospital, Belmont, MA, USA; Department of Psychiatry, Harvard Medical School, Boston, MA, USA. Electronic address: ymashhoon@mclean.harvard.edu.
authors.forename: Y
authors.initials: Y
authors.lastname: Mashhoon
authors.affiliation: Neurodevelopmental Laboratory on Addictions and Mental Health, McLean Hospital, Belmont, MA, USA; Department of Psychiatry, Harvard Medical School, Boston, MA, USA; Boston VA Healthcare System, Brockton, MA, USA; Harvard South Shore Residency Program, Brockton, MA, USA.
authors.forename: S
authors.initials: S
authors.lastname: Sava
authors.affiliation: Neurodevelopmental Laboratory on Addictions and Mental Health, McLean Hospital, Belmont, MA, USA; McLean Imaging Center, McLean Hospital, Belmont, MA, USA; Department of Psychiatry, Harvard Medical School, Boston, MA, USA.
authors.forename: J T
authors.initials: JT
authors.lastname: Sneider
authors.affiliation: Behavioral Psychopharmacology Research Laboratory, McLean Hospital, Belmont, MA, USA; McLean Imaging Center, McLean Hospital, Belmont, MA, USA; Department of Psychiatry, Harvard Medical School, Boston, MA, USA.
authors.forename: L D
authors.initials: LD
authors.lastname: Nickerson
authors.affiliation: Neurodevelopmental Laboratory on Addictions and Mental Health, McLean Hospital, Belmont, MA, USA; McLean Imaging Center, McLean Hospital, Belmont, MA, USA; Department of Psychiatry, Harvard Medical School, Boston, MA, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Silveri
mesh_terms: D000293:Adolescent; D000328:Adult; D000679:Amygdala / Q000473:pathology; D001284:Atrophy / Q000473:pathology; D002188:Cannabis / Q000009:adverse effects*; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000473:pathology*; D003072:Cognition Disorders / Q000473:pathology*; D005260:Female; D006624:Hippocampus / Q000473:pathology; D006801:Humans; D007175:Impulsive Behavior; D008279:Magnetic Resonance Imaging; D008297:Male; D002189:Marijuana Abuse / Q000473:pathology* / Q000523:psychology; D059906:Neuroimaging; D013788:Thalamus / Q000473:pathology*; D055815:Young Adult
keywords: Cortical thickness; Fusiform gyrus; Marijuana; Thalamus; Volume; Young adults