title: Age-related metabolic profiles in cognitively healthy elders: results from a voxel-based [18F]fluorodeoxyglucose-positron-emission tomography study with partial volume effects correction.
abstract: OBJECTIVE
  Functional brain variability has been scarcely investigated in cognitively healthy elderly subjects, and it is currently debated whether previous findings of regional metabolic variability are artifacts associated with brain atrophy. The primary purpose of this study was to test whether there is regional cerebral age-related hypometabolism specifically in later stages of life.
  
  
  METHODS
  MR imaging and FDG-PET data were acquired from 55 cognitively healthy elderly subjects, and voxel-based linear correlations between age and GM volume or regional cerebral metabolism were conducted by using SPM5 in images with and without correction for PVE. To investigate sex-specific differences in the pattern of brain aging, we repeated the above voxelwise calculations after dividing our sample by sex.
  
  
  RESULTS
  Our analysis revealed 2 large clusters of age-related metabolic decrease in the overall sample, 1 in the left orbitofrontal cortex and the other in the right temporolimbic region, encompassing the hippocampus, the parahippocampal gyrus, and the amygdala. The division of our sample by sex revealed significant sex-specific age-related metabolic decrease in the left temporolimbic region of men and in the left dorsolateral frontal cortex of women. When we applied atrophy correction to our PET data, none of the above-mentioned correlations remained significant.
  
  
  CONCLUSIONS
  Our findings suggest that age-related functional brain variability in cognitively healthy elderly individuals is largely secondary to the degree of regional brain atrophy, and the findings provide support to the notion that appropriate PVE correction is a key tool in neuroimaging investigations.
authors.affiliation: Neuroimaging in Psychiatry Laboratory, São Paulo University Medical School, Brazil.
authors.forename: P K
authors.initials: PK
authors.lastname: Curiati
authors.forename: J H
authors.initials: JH
authors.lastname: Tamashiro-Duran
authors.forename: F L S
authors.initials: FL
authors.lastname: Duran
authors.forename: C A
authors.initials: CA
authors.lastname: Buchpiguel
authors.forename: P
authors.initials: P
authors.lastname: Squarzoni
authors.forename: D C
authors.initials: DC
authors.lastname: Romano
authors.forename: H
authors.initials: H
authors.lastname: Vallada
authors.forename: P R
authors.initials: PR
authors.lastname: Menezes
authors.forename: M
authors.initials: M
authors.lastname: Scazufca
authors.forename: G F
authors.initials: GF
authors.lastname: Busatto
authors.forename: T C T F
authors.initials: TC
authors.lastname: Alves
mesh_terms: D000368:Aged; D000375:Aging / Q000378:metabolism*; D000465:Algorithms; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18