Changing topological patterns in normal aging using large-scale structural networks

Zhu, Wanlin; Wen, Wei; He, Yong; Xia, Aihua; Anstey, Kaarin J.; Sachdev, Perminder

doi:10.1016/j.neurobiolaging.2010.06.022

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Changing topological patterns in normal aging using large-scale structural networks

Wanlin Zhu
- School of Psychiatry, University of New South Wales, Sydney, Australia
- Neuropsychiatric Institute, Prince of Wales Hospital, Randwick, NSW, Australia
Wei Wen
- School of Psychiatry, University of New South Wales, Sydney, Australia
- Neuropsychiatric Institute, Prince of Wales Hospital, Randwick, NSW, Australia
- Corresponding author. Tel.: +61 2 93823730; fax: +61 2 93823774
Yong He
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China
Aihua Xia
- Department of Mathematics and Statistics, University of Melbourne, Melbourne, Australia
Kaarin J. Anstey
- Centre of Mental Health Research, Australian National University, Canberra, Australia
Perminder Sachdev
- School of Psychiatry, University of New South Wales, Sydney, Australia
- Neuropsychiatric Institute, Prince of Wales Hospital, Randwick, NSW, Australia

Received 20 October 2009; received in revised form 22 June 2010; accepted 29 June 2010. published online 19 August 2010.
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Abstract

We examine normal aging from the perspective of topological patterns of structural brain networks constructed from two healthy age cohorts 20 years apart. Based on graph theory, we constructed structural brain networks using 90 cortical and subcortical regions as a set of nodes and the interregional correlations of grey matter volumes across individual brains as edges between nodes, and further analyzed the topological properties of the age-specific networks. We found that the brain structural networks of both cohorts had small-world architecture, and the older cohort (N = 374; mean age = 66.6 years, range 64–68) had lower global efficiency but higher local clustering in the brain structural networks compared with the younger cohort (N = 428; mean age = 46.7, range 44–48). The older cohort had reduced hemispheric asymmetry and lower centrality of certain brain regions, such as the bilateral hippocampus, bilateral insula, left posterior cingulated, and right Heschl gyrus, but that of the prefrontal cortex (PFC) was not different. These structural network differences may provide the basis for changes in functional connectivity and indeed cognitive function as we grow older.

Keywords: Normal aging, Magnetic resonance imaging, Connectivity, Morphometry, Grey matter volume, Small world