title: Reduced white matter integrity and verbal fluency impairment in young adults with bipolar disorder: a diffusion tensor imaging study.
abstract: BACKGROUND
  Clinical evidence shows that bipolar disorder (BD) is characterized by white matter (WM) microstructural abnormalities. However, little is known about the biological mechanisms associated with these abnormalities and their relationship with cognitive functioning.
  
  
  METHODS
  49 adult BD patients ((M±SD): 29.27 ± 7.92 years; 17 males, 32 females; 34 BD-I, 10 BD-II, and 5 BD-NOS) and 28 age-matched normal subjects ((M±SD): 29.19 ± 7.35 years; 10 males and 18 females) underwent diffusion tensor imaging (DTI) imaging. DTI metrics were computed using whole-brain tract-based spatial statistics (TBSS) as part of the FMRIB Software Library. Measures of WM coherence (fractional anisotropy - FA) and axonal structure (mean, axial and radial diffusivity - MD, AD and RD) were employed to characterize the microstructural alterations in the limbic, commissural, association and projection fiber tracts. All participants performed the Brief Assessment of Cognition for Affective disorders (BAC-A).
  
  
  RESULTS
  BD patients performed poorly on verbal fluency tasks and exhibited large clusters of altered FA, RD and MD values within the retrolenticular part of the internal capsule, the superior and anterior corona radiata, and the corpus callosum. Increased FA values in the left IFOF and the forceps minor correlated positively with verbal fluency scores. Altered RD parameters in the corticospinal tract and the forceps minor were associated with reduced visuomotor abilities.
  
  
  CONCLUSIONS
  The reported verbal fluency deficits and FA, RD and MD alterations in WM structures are potential cognitive and neural markers of BD. Abnormal RD values may be associated with progressive demyelination.
authors: University of Texas Health Science Center at Houston, Department of Psychiatry and Behavioral Sciences, 77054 Houston, TX, United States. Electronic address: Isabelle.E.Bauer@uth.tmc.edu.
authors: Isabelle E
authors: IE
authors: Bauer
authors: Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States.
authors: Austin
authors: A
authors: Ouyang
authors: University of Texas Health Science Center at Houston, Department of Psychiatry and Behavioral Sciences, 77054 Houston, TX, United States.
authors: Benson
authors: B
authors: Mwangi
authors: University of Texas Health Science Center at Houston, Department of Psychiatry and Behavioral Sciences, 77054 Houston, TX, United States.
authors: Marsal
authors: M
authors: Sanches
authors: University of Texas Health Science Center at Houston, Department of Psychiatry and Behavioral Sciences, 77054 Houston, TX, United States.
authors: Giovana B
authors: GB
authors: Zunta-Soares
authors: Division of Medical Psychology, Duke University, Medical Centre, 27710 Durham, NC, United States.
authors: Richard S E
authors: RS
authors: Keefe
authors: Department of Radiology, Children's Hospital of Philadelphia, University of Pennsylvania PA, United States.
authors: Hao
authors: H
authors: Huang
authors: University of Texas Health Science Center at Houston, Department of Psychiatry and Behavioral Sciences, 77054 Houston, TX, United States.
authors: Jair C
authors: JC
authors: Soares
mesh_terms: D000328:Adult; D016880:Anisotropy; D001714:Bipolar Disorder / Q000150:complications* / Q000473:pathology*; D001931:Brain Mapping; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000209:etiology; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D015999:Multivariate Analysis; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D013064:Speech Disorders / Q000209:etiology*; D066127:White Matter / Q000473:pathology*; D055815:Young Adult
keywords: Bipolar disorder; Cognitive; Demyelination; Diffusion tensor imaging; TBSS