Brain elastography in aging relates to fluid/solid trendlines

Area of Science:

• Neuroscience
• Biophysics
• Biomedical Engineering

Background:

• Brain aging involves changes in morphology and composition.
• Brain elastography shows age-related softening of viscoelastic properties.
• Understanding these changes is crucial for diagnosing neurological conditions.

Purpose of the Study:

• Identify causal mechanisms driving age-related changes in brain viscoelasticity.
• Determine which structural factors influence grey and white matter stiffness over time.
• Clarify the role of brain elastography in studying aging, disease, and injury.

Main Methods:

• Analyzed elastography data from aging adults.
• Integrated data from a prior study on brain composition.
• Utilized a biophysical model of the brain's fluid/solid structure.

Main Results:

• Age-related increases in extracellular water and decreases in extracellular matrix significantly impact brain viscoelasticity.
• Grey matter stiffness decreases inversely with water fraction squared.
• White matter stiffness declines inversely with water fraction to the 2/3 power, reflecting axonal structure.

Conclusions:

• Brain elastography is sensitive to age-related changes in water and extracellular matrix.
• These findings highlight elastography as a macroscopic indicator of microscopic structural changes.
• Implications for clinical studies of aging, neurological disease, and brain injury.