title: Quantitative signal intensity measures on magnetic resonance imaging in attention-deficit hyperactivity disorder.
abstract: OBJECTIVE
  The aim of this study was to investigate possible abnormalities of cerebral myelination in subjects with attention-deficit hyperactivity disorder (ADHD).
  
  
  BACKGROUND
  Anatomic and functional neuroimaging studies of subjects with ADHD demonstrated a right frontostriatal deficit and abnormal cerebral asymmetries. Some also reported white matter abnormalities, such as smaller white matter volumes in the right anterior-superior frontal region, and the smaller bilateral retrocallosal region. Smaller volumes in specific areas of the corpus callosum have also been reported. We hypothesized that white matter signal intensities may also show differences indicating abnormal cerebral myelination.
  
  
  METHODS
  We analyzed T2-weighted magnetic resonance images of 11 adolescents with ADHD and 20 controls. Regions of interest were set in both the white and gray matter in frontal and parieto-occipital associative regions.
  
  
  RESULTS
  The ADHD group showed a higher signal intensity ratio, probably reflecting a higher degree of myelination. Significant interhemispheric differences emerged only in the posterior region in the ADHD group.
  
  
  CONCLUSIONS
  The higher degree of myelination in the right frontal region of ADHD may be due to a compensatory mechanism for the right frontostriatal dysfunction.
authors.affiliation: Department of Psychiatry and Clinical Psychobiology, University of Barcelona, Spain. rpueyo@psi.ub.es
authors.forename: Roser
authors.initials: R
authors.lastname: Pueyo
authors.forename: Cristina
authors.initials: C
authors.lastname: Mañeru
authors.forename: Carme
authors.initials: C
authors.lastname: Junqué
authors.forename: Pere
authors.initials: P
authors.lastname: Vendrell
authors.forename: Jesús
authors.initials: J
authors.lastname: Pujol
authors.forename: Maria
authors.initials: M
authors.lastname: Mataró
authors.forename: Armando
authors.initials: A
authors.lastname: Estévez-González
authors.forename: Carme
authors.initials: C
authors.lastname: García-Sánchez
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis*; D002540:Cerebral Cortex / Q000473:pathology*; D003337:Corpus Callosum / Q000473:pathology; D005260:Female; D005625:Frontal Lobe / Q000473:pathology*; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D012016:Reference Values