title: White matter integrity alterations in first episode, treatment-naive generalized anxiety disorder.
abstract: BACKGROUND
  Several neurobiological models of anxiety disorder posit a primary role for dysfunction of the amygdala and anterior cingulate cortex (ACC). This study tests the hypothesis that patients with generalized anxiety disorder (GAD) have abnormal white matter microstructure in the amygdala and ACC, as inferred from diffusion tensor imaging, compared with healthy controls.
  
  
  METHODS
  Subjects were 16 right-handed, first-episode, treatment-naive GAD patients without comorbid disorders and 26 matched, healthy comparison controls. All subjects underwent diffusion tensor imaging and structural magnetic resonance imaging brain scanning. Fractional anisotropy (FA), a robust intravoxel measure of water self-diffusion, was compared between groups on a voxel-by-voxel basis. Associations between clinical ratings of symptom severity (i.e., the Hamilton Anxiety Scale and the Penn State Worry Questionnaire) and FA were assessed.
  
  
  RESULTS
  Compared with healthy volunteers, patients demonstrated significantly higher FA in the right amygdala white matter and lower FA in the caudal ACC/mid-cingulate cortex white matter. Higher right amygdala FA correlated significantly with higher Hamilton Anxiety Scale scores and higher Penn State Worry Questionnaire scores.
  
  
  CONCLUSIONS
  The sample size was modest and may contribute to false positive effects.
  
  
  CONCLUSIONS
  These findings provide the first evidence of an abnormality in white matter microstructure that involves the amygdala and the cingulate cortex in the pathogenesis of GAD, and are consistent with neurobiological models that posit a defect in emotion-related brain regions.
authors.affiliation: Mental Health Institute, the Second Xiangya Hospital of Central South University, Changsha, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Lingjiang
authors.initials: L
authors.lastname: Li
authors.forename: Rongjun
authors.initials: R
authors.lastname: Yu
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Jinsong
authors.initials: J
authors.lastname: Tang
authors.forename: Liwen
authors.initials: L
authors.lastname: Tan
authors.forename: Mei
authors.initials: M
authors.lastname: Liao
authors.forename: Fan
authors.initials: F
authors.lastname: Yang
authors.forename: Baoci
authors.initials: B
authors.lastname: Shan
mesh_terms: D000328:Adult; D000679:Amygdala / Q000473:pathology*; D016880:Anisotropy; D001008:Anxiety Disorders / Q000473:pathology*; D016022:Case-Control Studies; D056324:Diffusion Tensor Imaging; D005260:Female; D006179:Gyrus Cinguli / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D011569:Psychiatric Status Rating Scales; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D055815:Young Adult