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bioRxiv · 10.1101/285536

Increased posterior default mode network activity and structural connectivity in young adult APOE-ε4 carriers: a multi-modal imaging investigation

Hodgetts, C. J.·Shine, J. P.·Williams, H.·Postans, M.·Sims, R.·Williams, J.·Lawrence, A. D.·Graham, K. S.
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Abstract

Young adult APOE-{varepsilon}4 carriers show increased activity in posterior regions of the default mode network (pDMN), but how this is related to structural connectivity is unknown. Thirty young adults (half APOE-{varepsilon}4 carriers, the other half APOE-{varepsilon}3{varepsilon}3/{varepsilon}2{varepsilon}3; mean age 20 years) were scanned using both diffusion and functional magnetic resonance imaging. Diffusion tractography was used to quantify the microstructure (mean diffusivity, MD; fractional anisotropy, FA) of the parahippocampal cingulum bundle (PHCB), which links pDMN and the medial temporal lobe. APOE-{varepsilon}4 carriers had lower MD and higher FA relative to non-carriers in PHCB. Further, PHCB microstructure was selectively associated with pDMN activity during a scene discrimination task known to be sensitive to Alzheimers disease (AD). These findings are consistent with a lifespan view of AD risk, where early-life structural and functional brain changes in specific, vulnerable networks leads to increased neural activity that may ultimately trigger amyloid-{beta} deposition.

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Hodgetts, C. J., Shine, J. P., Williams, H., Postans, M., Sims, R., Williams, J., Lawrence, A. D., Graham, K. S.. 2018-03-22. Increased posterior default mode network activity and structural connectivity in young adult APOE-ε4 carriers: a multi-modal imaging investigation. https://doi.org/10.1101/285536

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