Proton magnetic resonance spectroscopy in mild cognitive impairment and Alzheimer's disease: a preliminary study.

Background: Mild cognitive impairment (MCI) is recognized as a transitional clinical state between normal aging and Alzheimer's disease (AD) and has significant higher rate of progression to AD.

Objective: To compare the changes of metabolites between AD and MCI in specific locations of the brain by using Magnetic Resonance Spectroscopy (MRS).

Material And Method: MMSE-Thai 2002 and neuropsychological test were performed in 17 patients with memory problem, classified into AD and MCI (10, 7 patients respectively). All patients and three age-matched cognitively normal volunteers were examined with conventional MRI and MRS of the brain. Volumes of interest were located at both-sided frontal and parietal deep white matter. NAA/Cr, Cho/Cr and mI/Cr ratios of the patients were analyzed and statistically evaluated relative to cognitively normal volunteers. Statistical analysis was performed using Cohen's kappa coefficient and Kruskal-Wallis test.

Results: There was no statistically significant change in metabolites in all brain regions. For AD relative to cognitively normal volunteers, there were strong tendency toward statistically significant decreased NAA/Cr at the left frontal and left parietal regions (p = 0.043 each) and decreased Cho/Cr at the left frontal region (p = 0.028).

Conclusion: The changes of the metabolite ratios of MCI were much closer to AD. Strong tendency toward statistically significant decreased NAA/Cr in the left cerebral hemisphere, predominantly parietal region and strong tendency toward statistically significant decreased Cho/Cr at the left frontal region were indicative of neurodegeneration and replacement by gliosis. MRS may be useful for predict a chance that cognitively normal people may convert to the AD.