  Investigations of the human connectome have elucidated core features of adult
structural networks, particularly the crucial role of hub-regions. However,
little is known regarding network organisation of the healthy elderly
connectome, a crucial prelude to the systematic study of neurodegenerative
disorders. Here, whole-brain probabilistic tractography was performed on
high-angular diffusion-weighted images acquired from 115 healthy elderly
subjects, whom were 76 to 94 years old. Structural networks were reconstructed
between 512 cortical and subcortical brain regions. We sought to investigate
the architectural features of hub-regions, as well as left-right asymmetries,
and sexual dimorphisms. We observed that the topology of hub-regions is
consistent with adult connectomic data, and more importantly, their
architectural features reflect their ongoing vital role in network
communication. We also found substantial sexual dimorphisms, with females
exhibiting stronger inter-hemispheric connections between cingulate and
prefrontal cortices. Lastly, we demonstrate intriguing left-lateralized
subnetworks consistent with the neural circuitry specialised for language and
executive functions, while rightward subnetworks were dominant in visual and
visuospatial streams. These findings provide insights into healthy brain ageing
and provide a benchmark for the study of neurodegenerative disorders such as
Alzheimers disease and Frontotemporal Dementia.
