title: Altered cingulum bundle microstructure in autism spectrum disorder.
abstract: OBJECTIVE
  Here, we examined the cingulum bundle, a long-range white matter tract mediating dorsal limbic connectivity, using diffusion tensor imaging (DTI) tractography, in children and adolescents with autism spectrum disorder (ASD) versus controls. We hypothesised that cingulum bundle microstructure would be altered in ASD, based on evidence implicating abnormal white matter connectivity in this disorder.
  
  
  METHODS
  DTI data were acquired for 19 ASD participants (IQ ⩾ 70; 7-18 years; mean = 12.4 ± 3.1) and 16 age-matched controls (7-18 years; mean = 12.3 ± 3.6) on a 3 T magnetic resonance imaging system. Deterministic tractography was used to isolate the cingulum bundle. Left and right cingulum bundles were examined for differences in several DTI metrics in ASD children/adolescents versus controls, including: fractional anisotropy (FA), mean, axial, and radial diffusivity.
  
  
  RESULTS
  Significant age × group interaction effects were found for all DTI metrics (mean diffusivity: F 1,28 = 9.5, p = 0.005, radial diffusivity: F 1,28 = 7.8, p = 0.009, axial diffusivity: F 1,28 = 5.2, p = 0.03, FA: F 1,28 = 4.4, p = 0.04). Interaction effects were driven by increases in cingulum bundle diffusivity (mean, radial, and axial diffusivity), and decreased FA, in younger ASD participants within our sample versus controls.
  
  
  CONCLUSIONS
  Our results point to immature microstructural organisation of the cingulum bundle in ASD, particularly during the early years of life, with implications for limbic network synchronisation and complex socio-emotional performance.
authors.affiliation: 1 Department of Psychiatry, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
authors.forename: Stephanie H
authors.initials: SH
authors.lastname: Ameis
authors.affiliation: 2 Department of Psychology, Queens College, The City University of New York, Flushing, NY, USA.
authors.forename: Jin
authors.initials: J
authors.lastname: Fan
authors.affiliation: 1 Department of Psychiatry, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
authors.forename: Conrad
authors.initials: C
authors.lastname: Rockel
authors.affiliation: 3 Department of Psychiatry, Mount Sinai School of Medicine, New York, NY, USA.
authors.forename: Latha
authors.initials: L
authors.lastname: Soorya
authors.affiliation: 3 Department of Psychiatry, Mount Sinai School of Medicine, New York, NY, USA.
authors.forename: A Ting
authors.initials: AT
authors.lastname: Wang
authors.affiliation: 3 Department of Psychiatry, Mount Sinai School of Medicine, New York, NY, USA.
authors.forename: Evdokia
authors.initials: E
authors.lastname: Anagnostou