title: Association between microstructural integrity of frontostriatal tracts and school functioning: ADHD symptoms and executive function as mediators.
abstract: BACKGROUND
  Deficits in executive function (EF), impaired school functioning and altered white matter integrity in frontostriatal networks have been associated with attention-deficit/hyperactivity disorder (ADHD). However, relationships between impairments in these areas are unclear. Using a sample of youths with and without ADHD, this study examined the association between microstructural integrity of frontostriatal tracts and school dysfunction and the mediating roles of EF and ADHD symptoms in this association.
  
  
  METHODS
  The sample included 32 Taiwanese youths with ADHD and 32 age-, sex-, handedness- and IQ-matched typically-developing (TD) youths. Participants were assessed using psychiatric interviews, parent reports on ADHD symptoms and school functioning, and EF measures from the Cambridge Neuropsychological Test Automated Battery (CANTAB). The frontostriatal tracts were reconstructed by diffusion spectrum imaging (DSI) tractography and were subdivided into four functionally distinct segments: caudate-dorsolateral, caudate-medial prefrontal, caudate-orbitofrontal and caudate-ventrolateral tracts.
  
  
  RESULTS
  Youths with ADHD, relative to TD youths, showed altered white matter integrity in all four bilateral pairs of frontostriatal tracts (decreased general fractional anisotropy, GFA), had poor attention, vigilance and response inhibition, and showed impaired school functioning. Altered microstructural integrity in frontostriatal tracts was significantly associated with school dysfunction, which was mediated by EF measures of attention/vigilance and response inhibition in addition to inattention and hyperactivity symptoms.
  
  
  CONCLUSIONS
  Our findings demonstrate an association between white matter integrity in the frontostriatal networks and school functioning and suggest that EF deficits and ADHD symptoms may be the mediating mechanisms for this association. Future research is needed to test the directionality and specificity of this finding.
authors: Department of Psychiatry,National Taiwan University Hospital and College of Medicine,Taipei,Taiwan.
authors: S S
authors: SS
authors: Gau
authors: Institute of Child Development,University of Minnesota,Twin Cities, Minnesota, MN,USA.
authors: W-L
authors: WL
authors: Tseng
authors: Graduate Institute of Brain and Mind Sciences, College of Medicine,National Taiwan University,Taipei,Taiwan.
authors: W-Y I
authors: WY
authors: Tseng
authors: School of Medicine, College of Medicine,National Taiwan University,Taipei,Taiwan.
authors: Y-H
authors: YH
authors: Wu
authors: Center for Optoelectronic Medicine, College of Medicine,National Taiwan University,Taipei,Taiwan.
authors: Y-C
authors: YC
authors: Lo
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000503:physiopathology*; D016022:Case-Control Studies; D002648:Child; D056324:Diffusion Tensor Imaging; D056344:Executive Function; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D012574:Schools; D013624:Taiwan; D066127:White Matter / Q000503:physiopathology*
keywords: Attention-deficit/hyperactivity disorder; diffusion spectrum imaging tractography; executive function; frontostriatal tracts; mediators; school function