Regional metabolic patterns in mild cognitive impairment and Alzheimer's disease - A H-1 MRS study

Background: Mild cognitive impairment (MCI) is a recently described transit ional clinical state between normal aging and AD. Assuming that amnestic MC I patients had pathologic changes corresponding to an early phase and proba ble AD patients to a later phase of the disease progression, the authors co uld approximate the temporal course of proton MR spectroscopic (H-1 MRS) al terations in AD with a cross-sectional sampling scheme. Methods: The author s compared 1H MRS findings in the superior temporal lobe, posterior cingula te gyri, and medial occipital lobe in 21 patients with MCI, 21 patients wit h probable AD, and 63 elderly controls. These areas are known to be involve d at different neurofibrillary pathologic stages of An. Results: The N-acet ylaspartate (NAA)/creatine (Cr) ratios were significantly lower in AD patie nts compared to both MCI and normal control subjects in the left superior t emporal and the posterior cingulate volumes of interest (VOI) and there wer e no between-group differences in the medial occipital VOI. Myoinositol (Ml )/Cr ratios measured from the posterior cingulate VOI were significantly hi gher in both MCI and AD patients than controls. The choline (Cho)/Cr ratios measured from the posterior cingulate VOI were higher in AD patients compa red to both MCI and control subjects. Conclusion: These findings suggest th at the initial H-1 MRS change in the pathologic progression of AD is an inc rease in MI/Cr. A decrease in NAA/Cr and an increase in Cho/Cr develop late r in the disease course.