title: Altered prefrontal and insular cortical thickness in adolescent marijuana users.
abstract: BACKGROUND
  There are limited data regarding the impact of marijuana (MJ) on cortical development during adolescence. Adolescence is a period of substantial brain maturation and cortical thickness abnormalities may be indicative of disruptions of normal cortical development. This investigation applied cortical-surface based techniques to compare cortical thickness measures in MJ using adolescents compared to non-using controls.
  
  
  METHODS
  Eighteen adolescents with heavy MJ use and 18 non-using controls similar in age received MRI scans using a 3T Siemens scanner. Cortical reconstruction and volumetric segmentation was performed with FreeSurfer. Group differences in cortical thickness were assessed using statistical difference maps covarying for age and gender.
  
  
  RESULTS
  Compared to non-users, MJ users had decreased cortical thickness in right caudal middle frontal, bilateral insula and bilateral superior frontal cortices. Marijuana users had increased cortical thickness in the bilateral lingual, right superior temporal, right inferior parietal and left paracentral regions. In the MJ users, negative correlations were found between frontal and lingual regions for urinary cannabinoid levels and between age of onset of use and the right superior frontal gyrus.
  
  
  CONCLUSIONS
  This is one of the first studies to evaluate cortical thickness in a group of adolescents with heavy MJ use compared to non-users. Our findings are consistent with prior studies that documented abnormalities in prefrontal and insular regions. Our results suggest that age of regular use may be associated with altered prefrontal cortical gray matter development in adolescents. Furthermore, reduced insular cortical thickness may be a biological marker for increased risk of substance dependence.
authors.affiliation: The Brain Institute, University of Utah, Salt Lake City, UT 84108, USA. mlopez-larson@hsc.utah.edu
authors.forename: Melissa P
authors.initials: MP
authors.lastname: Lopez-Larson
authors.forename: Piotr
authors.initials: P
authors.lastname: Bogorodzki
authors.forename: Jadwiga
authors.initials: J
authors.lastname: Rogowska
authors.forename: Erin
authors.initials: E
authors.lastname: McGlade
authors.forename: Jace B
authors.initials: JB
authors.lastname: King
authors.forename: Janine
authors.initials: J
authors.lastname: Terry
authors.forename: Deborah
authors.initials: D
authors.lastname: Yurgelun-Todd
mesh_terms: D000293:Adolescent; D017668:Age of Onset; D001931:Brain Mapping; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D002189:Marijuana Abuse / Q000473:pathology*; D017397:Prefrontal Cortex / Q000473:pathology*; D011569:Psychiatric Status Rating Scales; D018709:Statistics, Nonparametric; D055815:Young Adult