title: Reduced integrity of the left arcuate fasciculus is specifically associated with auditory verbal hallucinations in schizophrenia.
abstract: BACKGROUND
  Schizophrenia patients with auditory verbal hallucinations (AVH) have reduced structural integrity in the left arcuate fasciculus (AFL) compared to healthy controls. However, it is neither known whether these changes are specific to AVH, as opposed to hallucinations or schizophrenia per se, nor how radial and/or axial diffusivity are altered. This study aimed to test the hypothesis that reductions to the structural integrity of the AFL are specifically associated with AVH in schizophrenia.
  
  
  METHODS
  Diffusion tensor imaging scans and clinical data were obtained from the Australian Schizophrenia Research Bank for 39 schizophrenia patients with lifetime AVH (18 current, 21 remitted), 74 schizophrenia patients with no lifetime AVH (40 with lifetime hallucinations in other modalities, 34 no lifetime hallucinations) and 40 healthy controls.
  
  
  RESULTS
  Fractional anisotropy was significantly reduced in the AFL of patients with lifetime AVH compared to both healthy controls (Cohen's d=1.24) and patients without lifetime AVH (d=.72), including compared to the specific subsets of patients without AVH who either had hallucinations in other modalities (d=.69) or no history of any hallucinations (d=.73). Radial, but not axial, diffusivity was significantly increased in patients with lifetime AVH compared to both healthy controls (d=.89) and patients without lifetime AVH (d=.39). Evidence was found for a non-linear relation between fractional anisotropy in the AFL and state AVH.
  
  
  CONCLUSIONS
  Reduced integrity of the AFL is specifically associated with AVH, as opposed to schizophrenia in general or hallucinations in other modalities. Increased radial diffusivity suggests dysmyelination or demyelination of the AFL may play a role in AVH.
authors: ARC Centre of Excellence in Cognition and its Disorders, Department of Cognitive Science, Macquarie University, Balaclava Road, North Ryde, NSW 2019, Australia. Electronic address: s.mccarthyjones@gmail.com.
authors: Simon
authors: S
authors: McCarthy-Jones
authors: School of Psychology, University of New South Wales, Sydney, NSW 2052, Australia.
authors: Lena K L
authors: LK
authors: Oestreich
authors: School of Psychology, University of New South Wales, Sydney, NSW 2052, Australia.
authors: Thomas J
authors: TJ
authors: Whitford
mesh_terms: D000328:Adult; D016880:Anisotropy; D001315:Australia; D001921:Brain / Q000473:pathology*; D056324:Diffusion Tensor Imaging; D005260:Female; D006212:Hallucinations / Q000188:drug therapy / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D008297:Male; D017711:Nonlinear Dynamics; D012559:Schizophrenia / Q000188:drug therapy / Q000473:pathology* / Q000503:physiopathology; D013067:Speech Perception; D066127:White Matter / Q000473:pathology*
keywords: Myelin; Neuroimaging; Psychosis; Quadratic