title: Disproportionate increases of white matter in right frontal lobe in Tourette syndrome.
abstract: OBJECTIVE
  Based on previous findings implicating abnormalities of cortico-striatal-thalamo-cortical circuitry in Tourette syndrome (TS), the authors performed a volumetric analysis of frontal and nonfrontal tissue (gray + white matter) in boys with TS, with and without attention deficit hyperactivity disorder (ADHD).
  
  
  METHODS
  Frontal and nonfrontal gray and white matter compartment volumes, obtained by a MRI protocol, were analyzed with a 2 x 2 factorial multivariate analysis of variance approach for associations with a TS or ADHD factor in 11 boys with TS only, 14 with TS + ADHD, 12 with ADHD only, and 26 healthy boys.
  
  
  RESULTS
  In subjects with TS, the right frontal lobe showed a larger proportion of white matter. In addition, results were consistent with previous reports of reduced frontal lobe volumes associated with ADHD. Our analyses suggested these reductions to be mainly the consequence of smaller gray matter volumes, particularly on the left.
  
  
  CONCLUSIONS
  These findings, suggesting the volumetric composition of frontal lobe tissue to be different in TS, support the hypothesis proposing frontostriatal pathway involvement in the pathophysiology of the disorder. Differences in composition of right frontal lobe attributable to white matter do not definitively implicate the hypothesized fiber pathways; however, considered in the context of the unilateral directionality of frontal-striatal circuitry, these results suggest the white matter connections as one explanation for basal ganglia anomalies (loss of normal left > right asymmetry) in TS.
authors.affiliation: aMRI Analysis Laboratory, Kennedy Krieger Institute, Baltimore, MD 21205, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Fredericksen
authors.forename: L E
authors.initials: LE
authors.lastname: Cutting
authors.forename: W R
authors.initials: WR
authors.lastname: Kates
authors.forename: S H
authors.initials: SH
authors.lastname: Mostofsky
authors.forename: H S
authors.initials: HS
authors.lastname: Singer
authors.forename: K L
authors.initials: KL
authors.lastname: Cooper
authors.forename: D C
authors.initials: DC
authors.lastname: Lanham
authors.forename: M B
authors.initials: MB
authors.lastname: Denckla
authors.forename: W E
authors.initials: WE
authors.lastname: Kaufmann
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D002648:Child; D005625:Frontal Lobe / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011569:Psychiatric Status Rating Scales; D005879:Tourette Syndrome / Q000473:pathology* / Q000523:psychology