title: Total brain volume and corpus callosum size in medication-naïve adolescents and young adults with autism spectrum disorder.
abstract: BACKGROUND
  Increased total brain volume (TBV) has been reported for children with autism spectrum disorder (ASD) but studies in older ASD subjects have been contradictory. Similarly, studies of corpus callosum (CC) area in ASD differ with regard to inclusion criteria, age, and IQ.
  
  
  METHODS
  In the present study, TBV, gray matter (GM), and white matter (WM) volume as well as midsagittal CC area were compared between 15 medication-naïve, high-functioning adolescent and young adult ASD subjects and 15 healthy control individuals, and correlations with visuomotor coordination and imitation abilities were explored. In addition, computational surface-based methods were implemented to encode callosal thickness at high spatial resolution.
  
  
  RESULTS
  Total brain volume, GM, and WM were increased and CC area was decreased in ASD subjects, a finding that was predominantly due to ASD subjects with lower IQ. Positive correlations of IQ with volume measures were observed only in control subjects. Autism spectrum disorder subjects showed reduced thickness in the posterior part of the CC. White matter volume showed a trend for negative correlation with dynamic balance and imitation abilities across groups.
  
  
  CONCLUSIONS
  This study replicates previous structural magnetic resonance imaging (MRI) findings in ASD, emphasizes the role of IQ differences, and adds some evidence for functional implications of structural findings.
authors.affiliation: Department of Child and Adolescent Psychiatry, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany. c.freitag@em.uni-frankfurt.de
authors.forename: Christine M
authors.initials: CM
authors.lastname: Freitag
authors.forename: Eileen
authors.initials: E
authors.lastname: Luders
authors.forename: Hanneke E
authors.initials: HE
authors.lastname: Hulst
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Narr
authors.forename: Paul M
authors.initials: PM
authors.lastname: Thompson
authors.forename: Arthur W
authors.initials: AW
authors.lastname: Toga
authors.forename: Christoph
authors.initials: C
authors.lastname: Krick
authors.forename: Carsten
authors.initials: C
authors.lastname: Konrad
mesh_terms: D000293:Adolescent; D001321:Autistic Disorder / Q000473:pathology* / Q000503:physiopathology / Q000523:psychology; D001921:Brain / Q000473:pathology* / Q000503:physiopathology; D016022:Case-Control Studies; D003337:Corpus Callosum / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007100:Imitative Behavior / Q000502:physiology; D007360:Intelligence; D007361:Intelligence Tests; D008297:Male; D009929:Organ Size; D011597:Psychomotor Performance / Q000502:physiology; D055815:Young Adult