Application of magnetic resonance spectroscopy for evaluating metabolic alteration in anterior cingulate cortex in Alzheimer's disease

Introduction: Alzheimer’s disease (AD) is the most common cause of dementia worldwide. Mild cognitive impairment (MCI) is often the prodromal stage to AD. Most patients with MCI harbor the pathologic changes of AD and demonstrate transition to AD at a rate of 10–15% per year. Accumulating evidence indicates that the asymmetry changes of left and right brain have happened in the early stage of AD. However, the features of asymmetry changes in anterior cingulate cortex (ACC) is still unclear. Materials and Methods: We examined the left-right asymmetry changes of metabolites in ACC. In this account, 14 cases of mild AD patients meeting criteria for probable AD of NINDS-ADRDA, 12 cases of MCI according to the Mayo Clinic Alzheimer’s Disease Research Center criteria, and 15 cases of age-matched normal controls (NC) received Proton magnetic resonance spectroscopy (1H-MRS) for measurement of NAA/mI, NAA/Cr, Cho/Cr, and mI/Cr ratios in the ACC bilaterally. We analyzed MRS data by paired t-test to validate the left-right asymmetry of MRS data in the ACC. Results: In AD, there was a significant difference in mI/Cr between the left and right ACC (P<0.001). In MCI, there was a significant difference in mI/Cr between the left and right ACC (P<0.001). In NC, there were no differences in the ratio value of metabolites NAA/mI, NAA/Cr, Cho/Cr, and mI/Cr between the left and right ACC. Conclusion: The left-right asymmetry of mI/Cr in the ACC may be an important biological indicator of mild AD.