The analysis of the neural metabolites in patients with global brain atrophy and different cognitive function in hippocampus and frontal cortex / 中华老年医学杂志

ABSTRACT

Objective Global brain atrophy was reported as an important structural change in Alzheimer's disease (AD), while it has been detected in the older person with normal cognitive function. Therefore, this study was aimed at investigating the difference of the neural metabolites in the left hippocampus (HIP) and left frontal cortex (FC) among patients who showed global brain atrophy but with different cognitive function. Methods The 33 patients with global brain atrophy confirmed by MRI scan, underwent a comprehensively clinical and neuropsychological assessment including mini-mental state examination (MMSE), activities of daily living scale (ADL) and clock drawing test(CDT). According to the diagnostic and statistical manual of mental disorders, fourth edition(DSM-Ⅳ) and Mayo clinic rochester(MCR), 14 patients were diagnosed as AD, 9 patients as amnestic mild cognitive impairment(aMCI), and 10 patients as normal cognition. Every person was taken a cerebral proton magnetic resonance spectroscopy(1H-MRS) scan to measure the levels of n-acetylaspartate(NAA), choline(Cho), myo-inositol(MI) and Creatine(Cr) in the left HIP and the left FC. Results While compared with the group with normal cognition, the ratio of NAA/Cr in the AD group reduced 10.2% in the left HIP and 5.3% in the left FC, and the ratio of Cho/Cr increased 17.5% in the left HIP and 16.7% in the left FC, and the ratio of MI/Cr increased 39.5% in the left HIP and 19.2% in the left FC. The ratio of NAA/Cr of the left HIP in the AD group was lower than that in the aMCI group at the decrease rate of 6.4%, while the ratio of NAA/Cr of the left FC was not significantly different between the two groups. The AD group had higher ratios of Cho/Cr at the increase rate of 9.3% in the HIP and 12.3% in the FC, and higher MI/Cr ratios at the increase rate of 30% in the HIP and 17% in the FC than in the aMCI group. The aMCI group showed significantly lower ratio of NAA/Cr at the decrease rate of 4.1% and higher ratio of Cho/Cr at the increase rate of 7.5% in the left HIP than in the normal cognition group. Conclusions Among patients with global brain atrophy, the decrement of ratio of NAA/Cr in the left HIP and the increment of the ratio of Cho/Cr and MI/Cr are predictive of the progress from aMCI to AD. Moreover, the decrement of ratio of NAA/Cr in the left HIP and the increment of the ratio of Cho/Cr are helpful to distinguish the aMCI and the persons with normal cognition.