Reduced N-acetylaspartate is consistent with axonal dysfunction in cerebral small vessel disease

Area of Science:

• Neuroimaging
• Neurology
• Biochemistry

Background:

• Cerebral small vessel disease (SVD) is a significant contributor to cognitive impairment, yet its underlying pathological mechanisms require further elucidation.
• Investigating brain metabolic alterations in SVD patients compared to controls is crucial for understanding disease progression.

Purpose of the Study:

• To utilize proton magnetic resonance spectroscopy (1H MRS) for assessing brain metabolic differences in SVD patients.
• To correlate observed metabolic changes with cognitive function in individuals with SVD.

Main Methods:

• Multi-voxel spectroscopic imaging of white matter was performed on 29 SVD patients and 35 controls.
• Absolute metabolite concentrations (N-acetylaspartate, creatines, cholines, myo-inositol, lactate) were quantified.
• Cognitive tests were administered to SVD patients, and composite scores were calculated.

Main Results:

• A significant reduction in N-acetylaspartate (NAA) was observed in SVD patients compared to controls (7.27% decrease, P=0.004).
• This NAA reduction was primarily attributed to lesion load within voxels, losing significance when adjusted for lesion volume (22% in SVD vs. 5% in controls, P<0.001).
• No significant correlation was found between cognitive scores and brain metabolite levels in SVD patients. Lactate was not detected.

Conclusions:

• The primary metabolic alteration in SVD is a decrease in NAA, indicating compromised neuronal integrity.
• The absence of correlation between NAA levels and cognitive performance suggests MRS is not a suitable surrogate marker for SVD.
• Further research is needed to fully understand the pathophysiology of SVD and its impact on cognition.