Changes in functional and structural brain connectome along the Alzheimer's disease continuum

Area of Science:

• Neuroscience
• Medical Imaging
• Network Science

Background:

• Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI) involve progressive neurodegeneration.
• Understanding brain network alterations is crucial for early diagnosis and tracking disease progression.
• The relationship between healthy brain connectivity and atrophy patterns in AD is not fully understood.

Purpose of the Study:

• To investigate structural and functional brain network architecture in AD and aMCI patients, stratified by conversion to AD.
• To assess how healthy brain network connectivity relates to brain atrophy topography along the AD continuum.

Main Methods:

• Utilized graph analysis and connectomics to assess structural and functional brain network properties.
• Studied 94 AD patients, 47 aMCI patients (25 converters), and 53 healthy controls.
• Assessed healthy topological features based on connectivity to the maximal atrophy epicenter.

Main Results:

• Brain network graph properties were severely altered in AD patients.
• Structural brain networks were altered in early converters (c-aMCI) compared to controls, particularly in temporal and parietal regions.
• Structural connectivity alterations differentiated c-aMCI from non-converters (nc-aMCI).
• The left hippocampus was the disease epicenter in AD and c-aMCI.
• Regions with strongest healthy functional connectivity to the epicenter showed the most atrophy.

Conclusions:

• Progressive degeneration in AD is linked to early breakdown of anatomical brain connections.
• The topography of brain connectional architecture may modulate the spread of AD.
• Structural network analysis can distinguish between MCI converters and non-converters.