Exploring Alzheimer’s disease network using social network analysis

Abstract

Alzheimer’s is a degenerative disease with changes occurring in different regions of the brain at different rates resulting in progressive deterioration. A lot of functional brain connectivity is altered, the process itself is insufficiently understood. In this work, an attempt is made to understand the progressive deterioration of the brain by locating the regions that show significant changes in the connectivity in the five lobes of the brain at different stages of the disease. Methods available in social network analysis like community and maximal clique analysis along with degree distributions, and centrality measures have been used to observe the network evolution of these regions at different stages. Networks of four diagnostic stages i.e., Normal, Early MCI (eMCI), Late MCI (lMCI), and Alzheimer’s Disease (AD), taken from ADNI (Alzheimer’s Disease Neuroimaging Initiative) database, are used for this study. Nine Regions of Interest (ROIs) from the five lobes are identified and a higher degree of change is observed in the connections of regions from the temporal and frontal lobes. There is a splurge of new connections in the eMCI stage for all regions except for those from the frontal lobe. We also observed more rearrangement among the left hemisphere nodes as compared to the right hemisphere nodes. There is an overall loss of edges between the normal and AD stages. This confirms that the study is able to identify the regions that are affected by the progression of the disease.