Impaired response of cerebral oxygen metabolism to visual stimulation in Huntington's disease

Area of Science:

• Neuroscience
• Medical Imaging
• Genetics

Background:

• Huntington's disease (HD) is a neurodegenerative disorder linked to CAG triplet repeat expansion in the Huntingtin gene.
• Metabolic and microvascular brain changes are implicated in early HD pathophysiology and functional decline.
• Investigating dynamic brain responses in premanifest and early HD is crucial for understanding disease progression.

Purpose of the Study:

• To investigate abnormalities in dynamic cerebral blood volume (CBV), cerebral blood flow (CBF), and cerebral metabolic rate of oxygen (CMRO2) responses to visual stimulation in HD patients.
• To assess the potential of these dynamic changes as biomarkers for early detection and monitoring of HD.
• To explore the role of metabolic alterations in the brain during the early stages of HD.

Main Methods:

• Utilized a novel 3-D-TRiple-acquisition-after-Inversion-Preparation MRI technique for simultaneous measurement of CBV, CBF, and CMRO2.
• Measured dynamic responses during visual stimulation in a single MRI scan.
• Included 23 HD patients (premanifest and early manifest) and 16 healthy controls.

Main Results:

• Premanifest and early manifest HD patients exhibited significantly decreased occipital cortex CMRO2 responses compared to controls (P < 0.001).
• Reduced CMRO2 response correlated with CAG-Age Product scores in HD patients (R² = 0.4, P = 0.001).
• No significant differences were noted in CBV or CBF responses between groups (data not shown).

Conclusions:

• Reduced CMRO2 response to visual stimulation may serve as a valuable imaging biomarker for Huntington's disease.
• These findings highlight the importance of metabolic dysfunction in the early stages of HD.
• Further research is warranted to validate this finding as a clinical biomarker for HD.