title: Regional brain chemical alterations in young children with autism spectrum disorder.
abstract: OBJECTIVE
  The authors evaluated regional brain chemistry for evidence of increased neuronal packing density in autism.
  
  
  METHODS
  Forty-five 3- to 4-year-old children with autism spectrum disorder (ASD), 13 children with typical development (TD), and 15 children with delayed development (DD) were studied using dual-echo proton echoplanar spectroscopic imaging (32 x 32 matrix-1 cm(3) voxels) to measure brain chemical concentrations and relaxation times. Chemical quantification was corrected for tissue partial volume and relative measures of chemical relaxation (T(2r)) were calculated from the paired echoes. Measures from averaged and individual regions were compared using analysis of variance corrected for multiple comparisons.
  
  
  RESULTS
  ASD subjects demonstrated reduced N-acetylaspartate (NAA) (-10%), creatine (Cre) (-8%), and myo-inositol (-13%) concentrations compared to TD controls and prolonged NAA T(2r) relative to TD (7%) and DD (9%) groups. Compared to DD subjects, children with ASD also demonstrated prolonged T(2r) for choline (10%) and Cre (9%). Regional analyses demonstrated subtle patterns of chemical alterations in ASD compared to the TD and DD groups.
  
  
  CONCLUSIONS
  Brain chemical abnormalities are present in ASD at 3 to 4 years of age. However, the direction and widespread distribution of these abnormalities do not support hypothesis of diffuse increased neuronal packing density in ASD.
authors.affiliation: Department of Radiology, University of Washington School of Medicine, Seattle 98105-6099, USA.
authors.forename: S D
authors.initials: SD
authors.lastname: Friedman
authors.forename: D W
authors.initials: DW
authors.lastname: Shaw
authors.forename: A A
authors.initials: AA
authors.lastname: Artru
authors.forename: T L
authors.initials: TL
authors.lastname: Richards
authors.forename: J
authors.initials: J
authors.lastname: Gardner
authors.forename: G
authors.initials: G
authors.lastname: Dawson
authors.forename: S
authors.initials: S
authors.lastname: Posse
authors.forename: S R
authors.initials: SR
authors.lastname: Dager
mesh_terms: D017677:Age Distribution; D000367:Age Factors; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism*; D001321:Autistic Disorder / Q000378:metabolism*; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism*; D002452:Cell Count; D002675:Child, Preschool; D002794:Choline / Q000032:analysis / Q000378:metabolism; D003401:Creatine / Q000032:analysis / Q000378:metabolism*; D002658:Developmental Disabilities / Q000378:metabolism*; D017352:Echo-Planar Imaging; D005260:Female; D006801:Humans; D007294:Inositol / Q000032:analysis / Q000378:metabolism*; D008297:Male; D009474:Neurons / Q000378:metabolism; D009483:Neuropsychological Tests; D012016:Reference Values; D017678:Sex Distribution
chemical_list: D001224:Aspartic Acid; D007294:Inositol; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline