title: Cognitive impairment with and without depression history: an analysis of white matter microstructure.
abstract: BACKGROUND
  Mild cognitive impairment (MCI) and late-life depression are clinical syndromes that often co-occur and may represent an early manifestation of neurodegenerative disease. The present study examined white matter microstructure in patients with MCI with and without a history of major depression compared with healthy controls.
  
  
  METHODS
  Older adults with MCI and no history of major depression (MCI), adults with MCI and euthymic major depression (MCI-MD) and healthy controls underwent comprehensive medical, psychiatric and neuropsychological assessments. Participants also underwent diffusion tensor imaging, which was analyzed using tract-based spatial statistics. White matter hyperintensity (WMH) burden and medical burden were also quantified.
  
  
  RESULTS
  We enrolled 30 participants in the MCI group, 36 in the MCI-MD group and 22 in the control group. Compared with controls, participants in the MCI group had significantly reduced fractional anisotropy (FA) in the corpus callosum, superior longitudinal fasciculus (SLF), corona radiata and posterior thalamic radiation. Participants in the MCI-MD group had significantly reduced FA in the corpus callosum, internal capsule, external capsule, corona radiata, posterior thalamic radiation, sagittal striatum, fornix, SLF, uncinate fasciculus and right cingulum compared with controls. No significant differences in FA were observed between the MCI and MCI-MD groups. Participants in the MCI-MD group had greater medical burden (p = 0.020) and WMH burden than controls (p = 0.013).
  
  
  CONCLUSIONS
  Study limitations include the cross-sectional design and antidepressant medication use.
  
  
  CONCLUSIONS
  To our knowledge, this study is the first to compare white matter microstructure in patients with MCI with and without a history of major depression and suggests that a common underlying structural white matter change may underpin cognitive impairment in both MCI groups. Further research is needed to delineate the pathophysiological mechanisms underlying these microstructural changes.
authors.affiliation: Ageing Brain Centre, Brain & Mind Research Institute, University of Sydney, Camperdown, Australia, and the Clinical Research Unit, Brain & Mind Research Institute, University of Sydney, Camperdown, Australia.
authors.forename: Shantel L
authors.initials: SL
authors.lastname: Duffy
authors.affiliation: Ageing Brain Centre, Brain & Mind Research Institute, University of Sydney, Camperdown, Australia, and the Clinical Research Unit, Brain & Mind Research Institute, University of Sydney, Camperdown, Australia.
authors.forename: Matt
authors.initials: M
authors.lastname: Paradise
authors.affiliation: Ageing Brain Centre, Brain & Mind Research Institute, University of Sydney, Camperdown, Australia, and the Clinical Research Unit, Brain & Mind Research Institute, University of Sydney, Camperdown, Australia.
authors.forename: Ian B
authors.initials: IB
authors.lastname: Hickie
authors.affiliation: Ageing Brain Centre, Brain & Mind Research Institute, University of Sydney, Camperdown, Australia, and the Clinical Research Unit, Brain & Mind Research Institute, University of Sydney, Camperdown, Australia.
authors.forename: Simon J G
authors.initials: SJ
authors.lastname: Lewis
authors.affiliation: Ageing Brain Centre, Brain & Mind Research Institute, University of Sydney, Camperdown, Australia, and the Clinical Research Unit, Brain & Mind Research Institute, University of Sydney, Camperdown, Australia.
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Naismith
authors.affiliation: Clinical Research Unit, Brain & Mind Research Institute, University of Sydney, Camperdown, Australia.
authors.forename: Jim
authors.initials: J
authors.lastname: Lagopoulos
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016880:Anisotropy; D001921:Brain / Q000473:pathology*; D060825:Cognitive Dysfunction / Q000150:complications / Q000473:pathology*; D003430:Cross-Sectional Studies; D003865:Major Depressive Disorder / Q000150:complications / Q000188:drug therapy / Q000473:pathology*; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D066127:White Matter / Q000473:pathology*