Beyond volumetry: Considering age-related changes in brain shape complexity using fractal dimensionality.

Area of Science:

• Neuroscience
• Brain Imaging
• Aging Research

Background:

• Brain gray matter volume, including cortical and subcortical structures and ventricles, changes with age.
• Age-related changes in brain structure involve not only volume but also cortical folding and overall brain shape.
• Standard volumetric measures may not fully capture the complexity of age-related structural brain alterations.

Purpose of the Study:

• To investigate the utility of fractal dimensionality as a sensitive measure of age-related changes in brain structure.
• To compare the effectiveness of fractal dimensionality against traditional volumetric measures in detecting structural differences across age groups.
• To highlight the implications of structural brain changes for neuroimaging analysis in aging populations.

Main Methods:

• Analysis of gray matter volume across cortical, subcortical, and ventricular regions.
• Assessment of age-related changes in cortical folding and brain shape.
• Application of fractal dimensionality as a measure of brain structure, evaluating both volumetric and shape-related aspects.
• Comparison of fractal dimensionality with volumetric measures for subcortical structures.

Main Results:

• Fractal dimensionality demonstrates higher sensitivity than traditional volume measures in detecting age-related structural differences in the brain.
• Both volumetric and shape-related changes contribute to age-related alterations in brain structure.
• Subcortical structures exhibit age-related shape variations in adjacent regions, not just isolated volume changes, which are better captured by fractal dimensionality.

Conclusions:

• Fractal dimensionality offers a more sensitive approach to quantifying age-related brain structural changes compared to volumetric analysis.
• Age-related brain alterations encompass complex changes in shape and folding, necessitating advanced analytical techniques.
• Standard normalization methods in brain function studies may be insufficient to account for significant inter-individual differences in cortical structure due to aging.