Abnormal Cortical Networks in Mild Cognitive Impairment and Alzheimer's Disease

Summary

Recently, many researchers have used graph theory to study the aberrant brain structures in Alzheimer's disease (AD) and have made great progress. However, the characteristics of the cortical network in Mild Cognitive Impairment (MCI) are still largely unexplored. In this study, the gray matter volumes obtained from magnetic resonance imaging (MRI) for all brain regions except the cerebellum were parcellated into 90 areas using the automated anatomical labeling (AAL) template to construct cortical networks for 98 normal controls (NCs), 113 MCIs and 91 ADs. The measurements of the network properties were calculated for each of the three groups respectively. We found that all three cortical networks exhibited small-world properties and those strong interhemispheric correlations existed between bilaterally homologous regions. Among the three cortical networks, we found the greatest clustering coefficient and the longest absolute path length in AD, which might indicate that the organization of the cortical network was the least optimal in AD. The small-world measures of the MCI network exhibited intermediate values. This finding is logical given that MCI is considered to be the transitional stage between normal aging and AD. Out of all the between-group differences in the clustering coefficient and absolute path length, only the differences between the AD and normal control groups were statistically significant. Compared with the normal controls, the MCI and AD groups retained their hub regions in the frontal lobe but showed a loss of hub regions in the temporal lobe. In addition, altered interregional correlations were detected in the parahippocampus gyrus, medial temporal lobe, cingulum, fusiform, medial frontal lobe, and orbital frontal gyrus in groups with MCI and AD. Similar to previous studies of functional connectivity, we also revealed increased interregional correlations within the local brain lobes and disrupted long distance interregional correlations in groups with MCI and AD.

Key Points

• 1Cortical networks in MCI and AD show small-world properties indicating efficient information transfer
• 2Interhemispheric correlations are strong across all three groups studied
• 3MCI is characterized by intermediate network measures between normal controls and AD
• 4Significant differences in clustering coefficients and absolute path lengths were found primarily between AD and normal controls
• 5Hub region analysis showed retention and loss of critical hubs in different brain areas among the groups.

Related articles

• Evaluating large language models for clinical note processing: local fine-tuning and internal-external validation using electronic health records from South Asia

  This research paper evaluates the effectiveness of large language models for processing clinical notes from electronic health records in South Asia, focusing on local fine-tuning and validation. It discusses the potential application of LLMs in clinical settings, particularly in resource-limited environments.

• Cardiac Cycle & Physiology: Understanding Cardiac Function

  This document provides a detailed overview of cardiac physiology, including the cardiac cycle, blood flow processes, and the cardiac conduction system. It aims to inform readers about the mechanics of the heart and its role in circulation.

• Cardiac Cycle & Physiology

  This document provides a comprehensive overview of cardiac cycle phases, blood flow through the heart, and the electrophysiology of cardiac conduction. It details the processes of deoxygenation and oxygenation of blood and the physiological aspects of cardiac output and common cardiovascular assessment findings.

• The Dual Pillars of Clinical and Community Care

  This document provides an in-depth examination of nutritional assessment and surveillance in clinical and community settings, offering guidelines on measuring malnutrition indicators and the importance of dietary interventions.

• Cather Simpson Lecture Research Brief Inaugural David Breen

  Cather Simpson Lecture Research Brief Inaugural David Breen Lecture | 14 October 2026 | 12 pm to 1 pm | AM103 The "Nespresso" of Diagnostics: Centrifugal Microfluidics for Point-of-Care Diagnostics; “Can we