Microstructural Tissue Changes in Alzheimer Disease Brains: Insights from Magnetization Transfer Imaging

Area of Science:

• Neuroimaging
• Neurology
• Biomarkers

Background:

• Reductions in Magnetization Transfer Ratio (MTR) are linked to microstructural damage in the brain.
• Alzheimer disease (AD) is characterized by progressive neurodegeneration and cognitive impairment.

Purpose of the Study:

• To compare MTR in gray matter (GM) and white matter (WM) between AD patients and healthy controls.
• To investigate the relationship between MTR and cognitive function in individuals with AD.

Main Methods:

• Prospective study involving 77 AD patients and 77 age-matched healthy controls.
• 3T MR imaging was used to determine MTR in various brain regions, including cortex, AD-signature regions, normal-appearing WM, and WM hyperintensities.

Main Results:

• MTR values were significantly lower in AD patients compared to controls across all investigated regions.
• Lower MTR in the cortex, AD-signature regions, normal-appearing WM, and WM hyperintensities were independent predictors of AD.
• Adjusting for atrophy and WM hyperintensities, lower GM MTR correlated with poorer cognitive functions, including global cognition, language, and constructional praxis.

Conclusions:

• Alzheimer disease is associated with reduced MTR in both GM and WM brain regions.
• Decreased MTR in cortical and AD-signature regions contributes to cognitive impairment, irrespective of brain atrophy and WM damage.