title: Impaired cerebrovascular hemodynamics are associated with cerebral white matter damage.
abstract: White matter hyperintensities (WMH) in elderly individuals with vascular diseases are presumed to be due to ischemic small vessel diseases; however, their etiology is unknown. We examined the cross-sectional relationship between cerebrovascular hemodynamics and white matter structural integrity in elderly individuals with vascular risk factors. White matter hyperintensity volumes, fractional anisotropy (FA), and mean diffusivity (MD) were obtained from MRI in 48 subjects (75±7years). Pulsatility index (PI) and dynamic cerebral autoregulation (dCA) was assessed using transcranial Doppler ultrasound of the middle cerebral artery. Dynamic cerebral autoregulation was calculated from transfer function analysis (phase and gain) of spontaneous blood pressure and flow velocity oscillations in the low (LF, 0.03 to 0.15 Hz) and high (HF, 0.16 to 0.5 Hz) frequency ranges. Higher PI was associated with greater WMH (P<0.005). Higher phase across all frequency ranges was associated with greater FA and lower MD (P<0.005). Lower gain was associated with higher FA in the LF range (P=0.001). These relationships between phase and FA were significant in the territories limited to the middle cerebral artery as well as across the entire brain. Our results show a strong relationship between impaired cerebrovascular hemodynamics (PI and dCA) and loss of cerebral white matter structural integrity (WMH and DTI metrics) in elderly individuals.
authors.affiliation: 1] Institute for Aging Research, Hebrew SeniorLife, Boston, Massachusetts, USA [2] Division of Gerontology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA [3] Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Sushmita
authors.initials: S
authors.lastname: Purkayastha
authors.affiliation: 1] Harvard Medical School, Boston, Massachusetts, USA [2] Department of Neurology, Stroke Division, Brigham and Women's Hospital, Boston, Massachusetts, USA.
authors.forename: Otite
authors.initials: O
authors.lastname: Fadar
authors.affiliation: Department of Neurology, Stroke Division, Brigham and Women's Hospital, Boston, Massachusetts, USA.
authors.forename: Aujan
authors.initials: A
authors.lastname: Mehregan
authors.affiliation: 1] Harvard Medical School, Boston, Massachusetts, USA [2] MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts, USA [3] Boston VA Healthcare System, Neuroimaging Research for Veterans Center, Boston, Massachusetts, USA.
authors.forename: David H
authors.initials: DH
authors.lastname: Salat
authors.affiliation: 1] Harvard Medical School, Boston, Massachusetts, USA [2] Center for Neurological Imaging, Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts, USA.
authors.forename: Nicola
authors.initials: N
authors.lastname: Moscufo
authors.affiliation: 1] Harvard Medical School, Boston, Massachusetts, USA [2] Center for Neurological Imaging, Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts, USA.
authors.forename: Dominik S
authors.initials: DS
authors.lastname: Meier
authors.affiliation: 1] Harvard Medical School, Boston, Massachusetts, USA [2] Center for Neurological Imaging, Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts, USA.
authors.forename: Charles Rg
authors.initials: CR
authors.lastname: Guttmann
authors.affiliation: 1] Harvard Medical School, Boston, Massachusetts, USA [2] Department of Medicine, Division of Endocrinology, Diabetes and Hypertension, Brigham and Women's Hospital, Boston, Massachusetts, USA.
authors.forename: Naomi Dl
authors.initials: ND
authors.lastname: Fisher
authors.affiliation: 1] Institute for Aging Research, Hebrew SeniorLife, Boston, Massachusetts, USA [2] Division of Gerontology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA [3] Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Lewis A
authors.initials: LA
authors.lastname: Lipsitz
authors.affiliation: 1] Institute for Aging Research, Hebrew SeniorLife, Boston, Massachusetts, USA [2] Harvard Medical School, Boston, Massachusetts, USA [3] Department of Neurology, Stroke Division, Brigham and Women's Hospital, Boston, Massachusetts, USA.
authors.forename: Farzaneh A
authors.initials: FA
authors.lastname: Sorond
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure; D002545:Brain Ischemia / Q000000981:diagnostic imaging / Q000503:physiopathology; D002540:Cerebral Cortex / Q000098:blood supply / Q000000981:diagnostic imaging / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D056784:Leukoencephalopathies / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D012307:Risk Factors; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods