title: Sex differences in human brain morphometry and metabolism: an in vivo quantitative magnetic resonance imaging and positron emission tomography study on the effect of aging.
abstract: BACKGROUND
  There are significant age and sex effects in cognitive ability and brain disease. However, sex differences in aging of human brain areas associated with nonreproductive behavior have not been extensively studied. We hypothesized that there would be significant sex differences in aging of brain areas that subserve speech, visuospatial, and memory function.
  
  
  METHODS
  We investigated sex differences in the effect of aging on human brain morphometry by means of volumetric magnetic resonance imaging and on regional cerebral metabolism for glucose by positron emission tomography. In the magnetic resonance imaging study, we examined 69 healthy right-handed subjects (34 women and 35 men), divided into young (age range, 20 to 35 years) and old (60 to 85 years) groups. In the positron emission tomography study, we investigated 120 healthy right-handed subjects (65 women and 55 men) aged 21 to 91 years.
  
  
  RESULTS
  In the magnetic resonance imaging study, age-related volume loss was significantly greater in men than women in whole brain and frontal and temporal lobes, whereas it was greater in women than men in hippocampus and parietal lobes. In the positron emission tomography study, significant sex differences existed in the effect of age on regional brain metabolism, and asymmetry of metabolism, in the temporal and parietal lobes, Broca's area, thalamus, and hippocampus.
  
  
  CONCLUSIONS
  We found significant sex differences in aging of brain areas that are essential to higher cognitive functioning. Thus, our findings may explain some of the age-sex differences in human cognition and response to brain injury and disease.
authors.affiliation: Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda, Md, USA.
authors.forename: D G
authors.initials: DG
authors.lastname: Murphy
authors.forename: C
authors.initials: C
authors.lastname: DeCarli
authors.forename: A R
authors.initials: AR
authors.lastname: McIntosh
authors.forename: E
authors.initials: E
authors.lastname: Daly
authors.forename: M J
authors.initials: MJ
authors.lastname: Mentis
authors.forename: P
authors.initials: P
authors.lastname: Pietrini
authors.forename: J
authors.initials: J
authors.lastname: Szczepanik
authors.forename: M B
authors.initials: MB
authors.lastname: Schapiro
authors.forename: C L
authors.initials: CL
authors.lastname: Grady
authors.forename: B
authors.initials: B
authors.lastname: Horwitz
authors.forename: S I
authors.initials: SI
authors.lastname: Rapoport
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism* / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology* / Q000378:metabolism* / Q000502:physiology; D003071:Cognition / Q000502:physiology; D005260:Female; D005625:Frontal Lobe / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology; D005947:Glucose / Q000378:metabolism; D006624:Hippocampus / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D010296:Parietal Lobe / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology; D012727:Sex Characteristics; D012737:Sex Factors; D013028:Space Perception / Q000502:physiology; D013060:Speech / Q000502:physiology; D013702:Temporal Lobe / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology; D014055:Tomography, Emission-Computed
chemical_list: D005947:Glucose