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From Vita Salute San Raffaele University (V.G., S.F.C., D.P.), Milan; San Raffaele Scientific Institute (V.G., S.F.C., F.F., D.P.), Milan; National Institute of Neuroscience (INN) (V.G., S.F.C., D.P.), Milan; Department of Neurology (B.B., A.P.), University of Brescia, Italy; Department of Neurology (E.K.), University of Cologne, Germany; Wolfson Molecular Imaging Centre (E.K., K.H.), University of Manchester, UK; Cyclotron Research Center (E.S.), University of Liège, Belgium; Department of Psychiatry and Psychotherapy (V.H.), Dresden University of Technology, Germany; Department of Neurological and Psychiatric Sciences (S.S.), University of Florence, Italy; Milano-Bicocca University (F.F.), Milan; and IBFM-CNR (F.F.), Milan, Italy.
Address correspondence and reprint requests to Dr. Valentina Garibotto, Via Olgettina, 58, 20132 Milan, Italy garibotto.valentina{at}hsr.it
Background: Previous reports have shown that higher education is associated with more severe brain pathology in patients with Alzheimer disease (AD), suggesting that these individuals have a functional reserve provided by education, which masks the clinical expression of a higher degree of neurodegeneration. It is unknown if a similar reserve mechanism exists in patients with amnestic mild cognitive impairment (aMCI). The aim of this study was to assess the impact of education and occupation on brain glucose metabolism (rCMRglc) measured with FDG-PET in aMCI and in a very large sample of subjects with probable AD (pAD).
Methods: A total of 242 patients with pAD, 72 with aMCI, and 144 healthy controls participated in the study. At follow-up, 21 subjects with aMCI progressed to AD. A regression analysis was conducted (SPM2), with education and occupation as independent variables, and rCMRglc as dependent variable, adjusting for demographic data, global cognitive status, and neuropsychological scores.
Results: The analysis showed a significant association between higher education/occupation and lower rCMRglc in posterior temporoparietal cortex and precuneus in pAD and aMCI converters, and no correlation in aMCI nonconverters and healthy controls. This means that, when submitted to FDG-PET for diagnostic evaluation, pAD and aMCI converters with higher education/occupation had, for comparable cognitive impairment, a more severe rCMRglc reduction than the ones with lower education/occupation.
Conclusions: This study suggests that education and occupation may be proxies for brain functional reserve, reducing the severity and delaying the clinical expression of Alzheimer disease (AD) pathology. The results in aMCI converters suggest that functional reserve is already at play in the predementia phase of AD.
Abbreviations: AD = Alzheimer disease; aMCI = amnestic mild cognitive impairment; BRH = brain reserve hypothesis; NEST-DD = Network for Efficiency and Standardization of Dementia Diagnosis; pAD = probable AD; PET = positron emission tomography; rCMRglc = regional cerebral metabolic activity; RI = reserve index.
Supplemental data at www.neurology.org
Supported by DIMI (Diagnostic Molecular Imaging), Sixth European Program, project no: LSHB-CT-2005-512146.
Disclosure: The authors report no disclosures.
Presented as a Platform Presentation at the 59th meeting of the American Academy of Neurology, Boston, May 1, 2007.
Received February 4, 2008. Accepted in final form July 7, 2008.
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