The Corticospinal Tract in Huntington's Disease

Area of Science:

• Neuroimaging
• Neurodegenerative Diseases
• White Matter Integrity

Background:

• Huntington's disease (HD) is a progressive neurodegenerative disorder.
• Motor impairment is a key characteristic of HD.
• The corticospinal tract (CST) is crucial for motor function, making its integrity vital in HD research.

Purpose of the Study:

• To investigate microstructural changes in the CST in presymptomatic (Pre-HD) and symptomatic HD subjects.
• To explore the role of iron accumulation in CST abnormalities.
• To correlate CST changes with disease progression markers.

Main Methods:

• Diffusion Tensor Imaging (DTI)-based tractography was used to analyze CST microstructure.
• T2*-weighted imaging assessed iron levels in the CST.
• 100 subjects (25 Pre-HD, 25 HD, 50 controls) were included.

Main Results:

• HD patients exhibited reduced fractional anisotropy (FA) and increased axial (AD) and radial diffusivity (RD) in the CST.
• Pre-HD subjects showed elevated iron in the left CST.
• CST microstructural changes correlated with CAG repeat length, age, and motor assessment scores (UHDRS).

Conclusions:

• Early white matter abnormalities in the CST are present in both presymptomatic and symptomatic HD.
• Increased iron in the presymptomatic phase supports a "dying back" hypothesis of axonal degeneration.
• Early iron accumulation may contribute to neurotoxicity and disease progression.