Hippocampus co-atrophy pattern in dementia deviates from covariance patterns across the lifespan

Area of Science:

• Neuroscience
• Neuroimaging
• Human Anatomy

Background:

• The hippocampus is crucial for memory and vulnerable to aging and dementia.
• Previous studies on hippocampal atrophy in aging/dementia used fixed models, yielding inconsistent findings.
• The organizational principles of hippocampal macrostructure across the lifespan and in disease remain unclear.

Purpose of the Study:

• To identify data-driven spatial patterns of hippocampal differentiation using structural covariance.
• To investigate if macrostructural changes follow cytoarchitectonic or functional organization in healthy aging and dementia.
• To provide robust spatial maps for future hippocampal research.

Main Methods:

• Cross-sectional study utilizing structural MRI data from 2594 participants.
• Applied a clustering algorithm to analyze voxel-wise structural covariance within the hippocampus.
• Examined healthy young, middle-aged, elderly, mild cognitive impairment, and dementia cohorts.

Main Results:

• A data-driven approach revealed distinct subdivisions within the hippocampus based on structural covariance.
• In healthy and mild cognitive impairment groups, the hippocampus differentiated into anterior, lateral, and medial subregions, aligning with cytoarchitectonic organization.
• In dementia patients, hippocampal subdivision mirrored functional organization into anterior, body, and tail regions.

Conclusions:

• Hippocampal structural organization differs between healthy aging and dementia.
• Findings suggest distinct patterns of co-plasticity and co-atrophy across the lifespan and in neurodegenerative disease.
• Provides novel, data-driven spatial maps of hippocampal differentiation for future research.