title: Hippocampal and entorhinal structures in subjective memory impairment: a combined MRI volumetric and DTI study.
abstract: Subjective memory impairment (SMI) is common among older adults. Increasing evidence suggests that SMI is a risk factor for future cognitive decline, as well as for mild cognitive impairment and dementia. Medial temporal lobe structures, including the hippocampus and entorhinal cortex, are affected in the early stages of Alzheimer's disease. The current study examined the gray matter (GM) volume and microstructural changes of hippocampal and entorhinal regions in individuals with SMI, compared with elderly control participants without memory complaints.
  
  
  
  A total of 45 participants (mean age: 70.31 ± 6.07 years) took part in the study, including 18 participants with SMI and 27 elderly controls without memory complaints. We compared the GM volume and diffusion tensor imaging (DTI) measures in the hippocampal and entorhinal regions between SMI and control groups.
  
  
  
  Individuals with SMI had lower entorhinal cortical volumes than control participants, but no differences in hippocampal volume were found between groups. In addition, SMI patients exhibited DTI changes (lower fractional anisotropy (FA) and higher mean diffusivity in SMI) in the hippocampal body and entorhinal white matter compared with controls. Combining entorhinal cortical volume and FA in the hippocampal body improved the accuracy of classification between SMI and control groups.
  
  
  
  These findings suggest that the entorhinal region exhibits macrostructural as well as microstructural changes in individuals with SMI, whereas the hippocampus exhibits only microstructural alterations.
authors.affiliation: Department of Neurology,Daejeon St. Mary's Hospital,College of Medicine,The Catholic University of Korea,Daejeon,South Korea.
authors.forename: Seon Young
authors.initials: SY
authors.lastname: Ryu
authors.affiliation: Department of Neurology,Yeouido St. Mary's Hospital,College of Medicine,The Catholic University of Korea,Seoul,South Korea.
authors.forename: Eun Ye
authors.initials: EY
authors.lastname: Lim
authors.affiliation: Department of Neurology,Seoul St. Mary's Hospital,College of Medicine,The Catholic University of Korea,Seoul,South Korea.
authors.forename: Seunghee
authors.initials: S
authors.lastname: Na
authors.affiliation: Department of Neurology,Bucheon St. Mary's Hospital,College of Medicine,The Catholic University of Korea,Bucheon,South Korea.
authors.forename: Yong Soo
authors.initials: YS
authors.lastname: Shim
authors.affiliation: Department of Neurology,Seoul St. Mary's Hospital,College of Medicine,The Catholic University of Korea,Seoul,South Korea.
authors.forename: Jung Hee
authors.initials: JH
authors.lastname: Cho
authors.affiliation: Department of Neurology,Konyang University Hospital,College of Medicine,Konyang University,Daejeon,South Korea.
authors.forename: Bora
authors.initials: B
authors.lastname: Yoon
authors.affiliation: Department of Neurology,Dong-A Medical Center,Dong-A University College of Medicine,Busan,South Korea.
authors.forename: Yun Jeong
authors.initials: YJ
authors.lastname: Hong
authors.affiliation: Department of Neurology,Seoul St. Mary's Hospital,College of Medicine,The Catholic University of Korea,Seoul,South Korea.
authors.forename: Dong Won
authors.initials: DW
authors.lastname: Yang
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000150:complications*; D016880:Anisotropy; D016022:Case-Control Studies; D056324:Diffusion Tensor Imaging; D005260:Female; D006624:Hippocampus / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D016015:Logistic Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008569:Memory Disorders / Q000000981:diagnostic imaging* / Q000209:etiology / Q000473:pathology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D012372:ROC Curve; D056910:Republic of Korea; D066127:White Matter / Q000000981:diagnostic imaging / Q000473:pathology*
keywords: MRI; diffusion tensor imaging; entorhinal cortex; hippocampus; subjective memory impairment