title: Cognitive reserve associated with FDG-PET in preclinical Alzheimer disease.
abstract: OBJECTIVE
  To examine the effect of education (a surrogate measure of cognitive reserve) on FDG-PET brain metabolism in elderly cognitively healthy (HC) subjects with preclinical Alzheimer disease (AD).
  
  
  METHODS
  Fifty-two HC subjects (mean age 75 years) with FDG-PET and CSF measurement of Aβ1-42 were included from the prospective Alzheimer's Disease Neuroimaging Initiative biomarker study. HC subjects received a research classification of preclinical AD if CSF Aβ1-42 was <192 pg/mL (Aβ1-42 [+]) vs HC with normal Aβ (Aβ1-42 [-]). In regression analyses, we tested the interaction effect between education and CSF Aβ1-42 status (Aβ1-42 [+] vs Aβ1-42 [-]) on FDG-PET metabolism in regions of interest (ROIs) (posterior cingulate, angular gyrus, inferior/middle temporal gyrus) and the whole brain (voxel-based).
  
  
  RESULTS
  An interaction between education and CSF Aβ1-42 status was observed for FDG-PET in the posterior cingulate (p < 0.001) and angular gyrus ROIs (p = 0.03), but was not significant for the inferior/middle temporal gyrus ROI (p = 0.06), controlled for age, sex, and global cognitive ability (Alzheimer's Disease Assessment Scale-cognitive subscale). The interaction effect was such that higher education was associated with lower FDG-PET in the Aβ1-42 (+) group, but with higher FDG-PET in the Aβ1-42 (-) group. Voxel-based analysis showed that this interaction effect was primarily restricted to temporo-parietal and ventral prefrontal brain areas.
  
  
  CONCLUSIONS
  Higher education was associated with lower FDG-PET in preclinical AD (Aβ1-42 [+]), suggesting that cognitive reserve had a compensatory function to sustain cognitive ability in presence of early AD pathology that alters FDG-PET metabolism.
authors.affiliation: Department of Radiology, University of California, San Francisco, CA, USA. michael.ewers@med.uni-muenchen.de
authors.forename: Michael
authors.initials: M
authors.lastname: Ewers
authors.forename: Philip S
authors.initials: PS
authors.lastname: Insel
authors.forename: Yaakov
authors.initials: Y
authors.lastname: Stern
authors.forename: Michael W
authors.initials: MW
authors.lastname: Weiner
mesh_terms: D001933:Brain Stem / Q000473:pathology*; D003071:Cognition / Q000502:physiology*; D003072:Cognition Disorders / Q000473:pathology*; D006801:Humans; D008125:Locus Coeruleus / Q000473:pathology*; D009474:Neurons / Q000473:pathology*