title: Impaired Frontolimbic Connectivity and Depressive Symptoms in Patients with Alzheimer's Disease.
abstract: Depressive symptoms are commonly observed in Alzheimer's disease (AD). The underlying mechanisms of depressive symptoms in AD remain unclear; frontolimbic circuitry dysfunction may play a role. We aimed to investigate the microstructural integrity of frontolimbic connectivity of specific fiber tracts in AD patients with and without depressive symptoms using diffusion tensor imaging (DTI).
  
  
  
  Eleven AD patients with depressive symptoms (dep-AD), 18 AD patients without depressive symptoms (nondep-AD), and 18 normal control (NC) subjects were included. The cingulum bundle (CB), uncinate fasciculus (UF), and fornix, mainly frontolimbic connectivity, were measured by DTI tractography and the metrics of fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity, and radial diffusivity (RD) were calculated.
  
  
  
  Compared with NC subjects, both dep-AD and nondep-AD patients showed significant differences for all indices in the fornix and significantly decreased FA and increased MD and RD in the bilateral CB and UF. When compared to nondep-AD patients, dep-AD patients showed significantly increased MD and RD in the bilateral CB and right UF.
  
  
  
  Depressive symptoms in AD patients may be involved in greater microstructural abnormalities of frontolimbic connectivity and myelin injury in the bilateral CB and right UF might contribute to the pathophysiology of depressive symptoms in AD.
authors.affiliation: Department of Neurology, The First Affiliated Hospital of China Medical University, Shenyang, China.
authors.forename: Qingyong
authors.initials: Q
authors.lastname: Zhu
authors.forename: Meiqing
authors.initials: M
authors.lastname: Lin
authors.forename: Siwei
authors.initials: S
authors.lastname: Bi
authors.forename: Zhiyan
authors.initials: Z
authors.lastname: Ni
authors.forename: Jiuhan
authors.initials: J
authors.lastname: Zhao
authors.forename: Boyu
authors.initials: B
authors.lastname: Chen
authors.forename: Guoguang
authors.initials: G
authors.lastname: Fan
authors.forename: Xiuli
authors.initials: X
authors.lastname: Shang
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology; D063132:Connectome / Q000379:methods; D003863:Depression / Q000175:diagnosis / Q000503:physiopathology; D056324:Diffusion Tensor Imaging / Q000379:methods; D005260:Female; D005625:Frontal Lobe / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008032:Limbic System / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male