Evolution of white matter tract microstructure across the life span

Area of Science:

• Neuroscience
• Human Lifespan Development
• Brain Imaging

Background:

• The human brain undergoes significant structural changes throughout life.
• Understanding white matter (WM) development and aging is crucial for cognitive health.
• Previous studies have indicated age-related changes in brain microstructure.

Purpose of the Study:

• To investigate tissue property dynamics across the human lifespan using advanced imaging techniques.
• To identify patterns of white matter maturation and aging.
• To test the 'last-in-first-out' retrogenesis hypothesis of aging.

Main Methods:

• Quantitative relaxometry and diffusion microstructure imaging applied to 801 individuals (aged 7-84).
• Diffusion tractography used to analyze white matter fascicles.
• Statistical analysis to identify nonlinear aging effects and correlational relationships.

Main Results:

• Significant nonlinear aging effects observed across various white matter tracts and tissue measures.
• Peak maturation timing varied considerably across different tissue measurements and tracts (heterochronicity).
• Strong correlation found between peak maturational timing and quadratic measurement differences, supporting the 'last-in-first-out' hypothesis for myelin-sensitive measures.

Conclusions:

• White matter maturation and aging are spatially heterogeneous and temporally varied across the lifespan.
• Multiple tissue measurements are essential for a comprehensive understanding of white matter aging.
• Findings provide a normative baseline for assessing developmental/degenerative disorders and investigating WM microstructure-cognition links.