Resting-state global functional connectivity as a biomarker of cognitive reserve in mild cognitive impairment

Nicolai Franzmeier, Miguel A. Araque Caballero, A. N. W. Taylor, Lee Simon-Vermot, Katharina Beurger, Birgit Ertl-Wagner, Claudia Mueller, Cihan Catak, Daniel Janowitz, Ebru Baykara, Benno Gesierich, Marco Duering, Michael Ewers

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Cognitive reserve (CR) shows protective effects in Alzheimer’s disease (AD) and reduces the risk of dementia. Despite the clinical significance of CR, a clinically useful diagnostic biomarker of brain changes underlying CR in AD is not available yet. Our aim was to develop a fully-automated approach applied to fMRI to produce a biomarker associated with CR in subjects at increased risk of AD. We computed resting-state global functional connectivity (GFC), i.e. the average connectivity strength, for each voxel within the cognitive control network, which may sustain CR due to its central role in higher cognitive function. In a training sample including 43 mild cognitive impairment (MCI) subjects and 24 healthy controls (HC), we found that MCI subjects with highCR (> median of years of education, CR+) showed increased frequency of high GFC values compared to MCI-CR- and HC. A summary index capturing such a surplus frequency of high GFC was computed (called GFC reserve (GFC-R) index).GFC-R discriminated MCI-CR+ vs. MCI-CR-, with the area under the ROC = 0.84. Cross-validation in an independently recruited test sample of 23 MCI subjects showed that higher levels of the GFC-R index predicted higher years of education and an alternative questionnaire-based proxy of CR, controlled for memory performance, gray matter of the cognitive control network, white matter hyperintensities, age, and gender. In conclusion, the GFC-R index that capturesGFC changes within the cognitive control network provides a biomarker candidate of functional brain changes of CR in patients at increased risk of AD.
Original languageEnglish
Pages (from-to)368-382
Number of pages15
JournalBrain Imaging and Behavior
Issue number2
Early online date05 Oct 2016
Publication statusPublished - 01 Apr 2017
Externally publishedYes


  • cognitive reserve
  • biomarker
  • mild cognitive impairment
  • Alzheimer's disease
  • global functional connectivity
  • resting-state fMRI
  • Cognitive reserve
  • Biomarker
  • Global functional connectivity
  • Alzheimer’s disease
  • Mild cognitive impairment
  • Resting-state fMRI
  • Humans
  • Magnetic Resonance Imaging/methods
  • Male
  • Reference Values
  • Connectome/methods
  • Rest
  • Sensitivity and Specificity
  • Cognitive Reserve
  • Female
  • Image Interpretation, Computer-Assisted/methods
  • Neural Pathways/physiopathology
  • Reproducibility of Results
  • Brain Mapping/methods
  • Nerve Net/physiopathology
  • Biomarkers
  • Aged
  • Cerebral Cortex/physiopathology
  • Cognitive Dysfunction/diagnostic imaging


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