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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.
GLOSSARY
- AD=
- Alzheimer disease;
- ADAS=
- Alzheimer’s Disease Assessment Scale;
- ADAS-cog=
- ADAS–cognitive subscale;
- ADNI=
- Alzheimer's Disease Neuroimaging Initiative;
- HC=
- cognitively healthy;
- MCI=
- mild cognitive impairment;
- PiB=
- Pittsburgh compound B;
- ROI=
- region of interest
Footnotes
Coinvestigators are listed on the Neurology® Web site at www.neurology.org.
Data used in preparation of this article were obtained from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database (adni.loni.ucla.edu). As such, the investigators within the ADNI contributed to the design and implementation of ADNI and/or provided data but did not participate in analysis or writing of this report. A complete listing of ADNI investigators can be found at http://adni.loni.ucla.edu/wpcontent/uploads/how_to_apply/ADNI_Acknowledgement_List.pdf.
Go to Neurology.org for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
Supplemental data at www.neurology.org
Editorial, page 1180
See page 1202
- Received August 29, 2012.
- Accepted December 6, 2012.
- © 2013 American Academy of Neurology
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