title: Sex differences of human cortical blood flow and energy metabolism.
abstract: Brain energy metabolism is held to reflect energy demanding processes in neuropil related to the density and activity of synapses. There is recent evidence that men have higher density of synapses in temporal cortex than women. One consequence of these differences would be different rates of cortical energy turnover and blood flow in men and women. To test the hypotheses that rates of oxygen consumption (CMRO2) and cerebral blood flow are higher in men than in women in regions of cerebral cortex, and that the differences persist with aging, we used positron emission tomography to determine cerebral blood flow and cerebral metabolic rate of oxygen as functions of age in healthy volunteers of both sexes. Cerebral metabolic rate of oxygen did not change with age for either sex and there were no differences of mean values of cerebral metabolic rate of oxygen between men and women in cerebral cortex. Women had significant decreases of cerebral blood flow as function of age in frontal and parietal lobes. Young women had significantly higher cerebral blood flow than men in frontal and temporal lobes, but these differences had disappeared at age 65. The absent sex difference of cerebral energy turnover suggests that the known differences of synaptic density between the sexes are counteracted by opposite differences of individual synaptic activity.
authors.affiliation: 1 Department of Nuclear Medicine and PET Center, Aarhus University Hospitals, Aarhus, Denmark.
authors.forename: Joel
authors.initials: J
authors.lastname: Aanerud
authors.affiliation: 1 Department of Nuclear Medicine and PET Center, Aarhus University Hospitals, Aarhus, Denmark.
authors.forename: Per
authors.initials: P
authors.lastname: Borghammer
authors.affiliation: 2 Centre for Clinical Research, University of Queensland, Australia.
authors.forename: Anders
authors.initials: A
authors.lastname: Rodell
authors.affiliation: 3 Departement of Mathematics, Aarhus University, Aarhus, Denmark.
authors.forename: Kristjana Y
authors.initials: KY
authors.lastname: Jónsdottir
authors.affiliation: 4 Center for Functionally Integrative Neuroscience, University of Aarhus, Aarhus, Denmark.|5 Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark.|6 Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, USA.|7 Department of Neurology and Neurosurgery, McGill University, Montréal, Québec, Canada.
authors.forename: Albert
authors.initials: A
authors.lastname: Gjedde
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism / Q000502:physiology; D001783:Blood Flow Velocity / Q000502:physiology*; D002540:Cerebral Cortex / Q000098:blood supply / Q000000981:diagnostic imaging / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D049268:Positron-Emission Tomography; D012727:Sex Characteristics; D055815:Young Adult
keywords: Aging; cerebral blood flow measurement; energy metabolism; gender; positron emission tomography