Graph Theoretic Analysis of Structural Connectivity Across the Spectrum of Alzheimer's Disease: The Importance of Graph Creation Methods

• Activity Number: 243
• Type: Contributed
• Date/Time: Monday, August 10, 2015 : 2:00 PM to 3:50 PM
• Sponsor: Mental Health Statistics Section
• Author(s): David Ruth* and David Phillips and Alec McGlaughlin and Leah Jager and Anja Soldan
• Companies: U.S. Naval Academy and U.S. Naval Academy and U.S. Naval Academy and The Johns Hopkins University and The Johns Hopkins University
• Keywords: Graph theory ; Structural MRI ; Alzheimer's disease ; Mild cognitive impairment ; Connectomics ; Cortical thickness networks

Abstract

Graph theory is increasingly being used to study brain connectivity across the spectrum of Alzheimer's disease (AD), but prior findings have been inconsistent, likely reflecting methodological differences. We systematically investigated how methods of graph creation affect structural network properties and group differences. Four groups were compared: cognitively normal older adults, individuals with stable Mild Cognitive Impairment (MCI), with progressive MCI, and with AD-dementia. Small-world measures of connectivity differed across groups, consistent with prior studies. The Randi? index best discriminated among groups and differentiated the stable and progressive MCI groups, suggesting that it might be useful for tracking and predicting the progression of AD. However, the magnitude and direction of group differences were dependent on the method of graph creation, indicating that it is crucial to take into account how graphs are constructed when interpreting differences across groups. Algebraic connectivity measures showed few group differences, independent of graph construction method, suggesting that global connectivity as it relates to node degree is not altered in early AD.