title: Multi-modal MRI investigation of volumetric and microstructural changes in the hippocampus and its subfields in mild cognitive impairment, Alzheimer's disease, and dementia with Lewy bodies.
abstract: Volumetric atrophy and microstructural alterations in diffusion tensor imaging (DTI) measures of the hippocampus have been reported in people with Alzheimer's disease (AD) and mild cognitive impairment (MCI). However, no study to date has jointly investigated concomitant microstructural and volumetric changes of the hippocampus in dementia with Lewy bodies (DLB).
  
  
  
  A total of 84 subjects (23 MCI, 17 DLB, 14 AD, and 30 healthy controls) were recruited for a multi-modal imaging (3T MRI and DTI) study that included neuropsychological evaluation. Freesurfer was used to segment the total hippocampus and delineate its subfields. The hippocampal segmentations were co-registered to the mean diffusivity (MD) and fractional anisotropy (FA) maps obtained from the DTI images.
  
  
  
  Both AD and MCI groups showed significantly smaller hippocampal volumes compared to DLB and controls, predominantly in the CA1 and subiculum subfields. Compared to controls, hippocampal MD was elevated in AD, but not in MCI. DLB was characterized by both volumetric and microstructural preservation of the hippocampus. In MCI, higher hippocampal MD was associated with greater atrophy of the hippocampus and CA1 region. Hippocampal volume was a stronger predictor of memory scores compared to MD within the MCI group.
  
  
  
  Through a multi-modal integration, we report novel evidence that the hippocampus in DLB is characterized by both macrostructural and microstructural preservation. Contrary to recent suggestions, our findings do not support the view that DTI measurements of the hippocampus are superior to volumetric changes in characterizing group differences, particularly between MCI and controls.
authors.affiliation: Department of Psychiatry,University of Cambridge,UK.
authors.forename: Elijah
authors.initials: E
authors.lastname: Mak
authors.affiliation: Department of Psychiatry,University of Cambridge,UK.
authors.forename: Silvy
authors.initials: S
authors.lastname: Gabel
authors.affiliation: Department of Psychiatry,University of Cambridge,UK.
authors.forename: Li
authors.initials: L
authors.lastname: Su
authors.affiliation: Wolfson Brain Imaging Centre,University of Cambridge,UK.
authors.forename: Guy B
authors.initials: GB
authors.lastname: Williams
authors.affiliation: Department of Psychiatry,University of Cambridge,UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Arnold
authors.affiliation: Department of Clinical Neurosciences,University of Cambridge,Cambridge,UK.
authors.forename: Luca
authors.initials: L
authors.lastname: Passamonti
authors.affiliation: Department of Clinical Neurosciences,University of Cambridge,Cambridge,UK.
authors.forename: Patricia
authors.initials: P
authors.lastname: Vazquez Rodríguez
authors.affiliation: Department of Psychiatry,University of Cambridge,UK.
authors.forename: Ajenthan
authors.initials: A
authors.lastname: Surendranathan
authors.affiliation: Department of Psychiatry,University of Cambridge,UK.
authors.forename: W Richard
authors.initials: WR
authors.lastname: Bevan-Jones
authors.affiliation: Department of Clinical Neurosciences,University of Cambridge,Cambridge,UK.
authors.forename: James B
authors.initials: JB
authors.lastname: Rowe
authors.affiliation: Department of Psychiatry,University of Cambridge,UK.
authors.forename: John T
authors.initials: JT
authors.lastname: O'Brien
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000000981:diagnostic imaging*; D001284:Atrophy / Q000473:pathology; D016022:Case-Control Studies; D060825:Cognitive Dysfunction / Q000000981:diagnostic imaging*; D056324:Diffusion Tensor Imaging / Q000379:methods; D005260:Female; D006624:Hippocampus / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D020961:Lewy Body Disease / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009483:Neuropsychological Tests; D012044:Regression Analysis; D006113:United Kingdom
keywords: Alzheimer's disease; MRI; cognitive impairment; dementia with Lewy bodies; diffusion MRI; neuroimaging