title: Accelerated decline in white matter integrity in clinically normal individuals at risk for Alzheimer's disease.
abstract: Prior studies have identified white matter abnormalities in Alzheimer's disease (AD). Yet, cross-sectional studies in normal older individuals show little evidence for an association between markers of AD risk (APOE4 genotype and amyloid deposition), and white matter integrity. Here, 108 normal older adults (age, 66-87) with assessments of apolipoprotein e4 (APOE4) genotype and assessment of amyloid burden by positron emission tomography underwent diffusion tensor imaging scans for measuring white matter integrity at 2 time points, on average 2.6 years apart. Linear mixed-effects models showed that amyloid burden at baseline was associated with steeper decline in fractional anisotropy in the parahippocampal cingulum (p < 0.05). This association was not significant between baseline measures suggesting that longitudinal analyses can provide novel insights that are not detectable in cross-sectional designs. Amyloid-related changes in hippocampus volume did not explain the association between amyloid burden and change in fractional anisotropy. The results suggest that accumulation of cortical amyloid and white matter changes in parahippocampal cingulum are not independent processes in individuals at increased risk for AD.
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA; Department of Radiation Sciences, Diagnostic Radiology, Umeå University, Umeå, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Rieckmann
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA; Department of Psychology and Center for Brain Science, Harvard University, Cambridge, MA, USA.
authors.forename: Koene R A
authors.initials: KR
authors.lastname: Van Dijk
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA; Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Center for Alzheimer Research and Treatment, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Reisa A
authors.initials: RA
authors.lastname: Sperling
authors.affiliation: Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Center for Alzheimer Research and Treatment, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA; Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Keith A
authors.initials: KA
authors.lastname: Johnson
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA; Department of Psychology and Center for Brain Science, Harvard University, Cambridge, MA, USA; Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Randy L
authors.initials: RL
authors.lastname: Buckner
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA; Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA. Electronic address: hedden@nmr.mgh.harvard.edu.
authors.forename: Trey
authors.initials: T
authors.lastname: Hedden
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology; D000544:Alzheimer Disease / Q000209:etiology; D016229:Amyloid beta-Peptides / Q000378:metabolism; D001057:Apolipoproteins E / Q000235:genetics; D056324:Diffusion Tensor Imaging; D005260:Female; D005838:Genotype; D006624:Hippocampus / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008297:Male; D012306:Risk; D066127:White Matter / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology*
chemical_list: D016229:Amyloid beta-Peptides; D001057:Apolipoproteins E
keywords: Aging; Amyloid; Diffusion tensor imaging; Longitudinal; White matter