title: Callous-unemotional traits drive reduced white-matter integrity in youths with conduct problems.
abstract: BACKGROUND
  Callous-unemotional (CU) traits represent a significant risk factor for severe and persistent conduct problems in children and adolescents. Extensive neuroimaging research links CU traits to structural and functional abnormalities in the amygdala and ventromedial prefrontal cortex. In addition, adults with psychopathy (a disorder for which CU traits are a developmental precursor) exhibit reduced integrity in uncinate fasciculus, a white-matter (WM) tract that connects prefrontal and temporal regions. However, research in adolescents has not yet yielded similarly consistent findings.
  
  
  METHODS
  We simultaneously modeled CU traits and externalizing behaviors as continuous traits, while controlling for age and IQ, in order to identify the unique relationship of each variable with WM microstructural integrity, assessed using diffusion tensor imaging. We used tract-based spatial statistics to evaluate fractional anisotropy, an index of WM integrity, in uncinate fasciculus and stria terminalis in 47 youths aged 10-17 years, of whom 26 exhibited conduct problems and varying levels of CU traits.
  
  
  RESULTS
  Whereas both CU traits and externalizing behaviors were negatively correlated with WM integrity in bilateral uncinate fasciculus and stria terminalis/fornix, simultaneously modeling both variables revealed that these effects were driven by CU traits; the severity of externalizing behavior was not related to WM integrity after controlling for CU traits.
  
  
  CONCLUSIONS
  These results indicate that WM abnormalities similar to those observed in adult populations with psychopathy may emerge in late childhood or early adolescence, and may be critical to understanding the social and affective deficits observed in this population.
authors.affiliation: Department of Psychology,Georgetown University,Washington,DC,USA.
authors.forename: A L
authors.initials: AL
authors.lastname: Breeden
authors.affiliation: Department of Psychology,Georgetown University,Washington,DC,USA.
authors.forename: E M
authors.initials: EM
authors.lastname: Cardinale
authors.affiliation: Department of Neurology,Georgetown University,Washington,DC,USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Lozier
authors.affiliation: Department of Neurology,Georgetown University,Washington,DC,USA.
authors.forename: J W
authors.initials: JW
authors.lastname: VanMeter
authors.affiliation: Department of Psychology,Georgetown University,Washington,DC,USA.
authors.forename: A A
authors.initials: AA
authors.lastname: Marsh
mesh_terms: D000293:Adolescent; D000679:Amygdala / Q000503:physiopathology*; D002648:Child; D019955:Conduct Disorder / Q000503:physiopathology* / Q000523:psychology*; D056324:Diffusion Tensor Imaging; D004645:Empathy; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D000066553:Problem Behavior / Q000523:psychology*; D066127:White Matter / Q000503:physiopathology*
keywords: Callous-unemotional traits; conduct problems; diffusion tensor imaging; uncinate fasciculus; white matter