title: Alzheimer's Disease Disrupts Rich Club Organization in Brain Connectivity Networks.
abstract: Diffusion imaging and brain connectivity analyses can monitor white matter deterioration, revealing how neural pathways break down in aging and Alzheimer's disease (AD). Here we tested how AD disrupts the 'rich club' effect - a network property found in the normal brain - where high-degree nodes in the connectivity network are more heavily interconnected with each other than expected by chance. We analyzed 3-Tesla whole-brain diffusionweighted images (DWI) from 66 subjects (22 AD/44 normal elderly). We performed whole-brain tractography based on the orientation distribution functions. Connectivity matrices were compiled, representing the proportion of detected fibers interconnecting 68 cortical regions. As expected, AD patients had a lower nodal degree (average number of connections) in cortical regions implicated in the disease. Unexpectedly, the normalized rich club coefficient was higher in AD. AD disrupts cortical networks by removing connections; when these networks are thresholded, organizational properties are disrupted leading to additional new biomarkers of AD.
authors: Imaging Genetics Center, Laboratory of Neuro Imaging, UCLA School of Medicine, Los Angeles, CA, USA.
authors: Madelaine
authors: M
authors: Daianu
authors: Imaging Genetics Center, Laboratory of Neuro Imaging, UCLA School of Medicine, Los Angeles, CA, USA.
authors: Emily L
authors: EL
authors: Dennis
authors: Imaging Genetics Center, Laboratory of Neuro Imaging, UCLA School of Medicine, Los Angeles, CA, USA.
authors: Neda
authors: N
authors: Jahanshad
authors: Imaging Genetics Center, Laboratory of Neuro Imaging, UCLA School of Medicine, Los Angeles, CA, USA.
authors: Talia M
authors: TM
authors: Nir
authors: Imaging Genetics Center, Laboratory of Neuro Imaging, UCLA School of Medicine, Los Angeles, CA, USA.
authors: Arthur W
authors: AW
authors: Toga
authors: Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
authors: Clifford R
authors: CR
authors: Jack
authors: Department of Radiology, Medicine, and Psychiatry, University of California San Francisco, CA, USA ; Department of Veterans Affairs Medical Center, San Francisco, CA, USA.
authors: Michael W
authors: MW
authors: Weiner
authors: Imaging Genetics Center, Laboratory of Neuro Imaging, UCLA School of Medicine, Los Angeles, CA, USA.
authors: Paul M
authors: PM
authors: Thompson