Using Proton Magnetic Resonance Spectroscopy In Alzheimer’s Disease To Analyze The Metabolites Changes In Hippocampus

Objective Alzheimer’s disease is a progressive neurodegenerative disease, which symbolized as cognitive impairment and behavioral disorder. With an aggravated aging level, the morbidity of the disease and the social problems it triggered has attracted so much attention around the world. According to the study of AD, the former studies tended to be interested in the changes of brain structure. Now some studies have indicated that cerebral metabolism changes appeared earlier than encephalatrophy caused by the changes of brain structure. Magnetic resonance spectroscopy is a imaging method which enables us to detect the change of metabolism in vivo tissues and organs non-invasively, and the values it shows in diagnosis and differential diagnosis is significant. In this paper, we use 3.0T proton magnetic resonance spectroscopy to compare the metabolism changes of bilateral hippocampus between AD patients and healthy volunteers, combining neuropsychological tests to understand the pathological development process of AD, and to seek more exact access to diagnose AD in early stages.Methods All AD patients and normal controls, amount to 58, come from the first hospital affiliated to Dalian Medical University neurology departments. We choose the bilateral hippocampus as the region of interest and analyze the spectral data which obtained by using 3.0T short-echo-time 1H MRS. Here we got N-acetylaspartate(NAA)/creatine(Cr) 、Choline(Cho)/Cr、Myo-inistol(m I)/Cr and NAA/m I ratios of the bilateral hippocampus among the two groups. Each member accepted the neuropsychological tests including MMSE、Mo CA and ADL. We used statistical method to compare metabolite changes between AD patients and normal controls and to detect the correlations between cognitive impairment,the abilities of daily life and metabolism changes.Results1. In the two groups, there was no significant difference in age, sex and education level(P=0.816,P=0.185,P=0.204). The scores of MMSE and Mo CA were decreased in AD patients when compared to the healthy control groups(All P<0.001), and the scores of ADL in AD patients were higher than the normal controls(All P<0.001).2. In the bilateral hippocampus of the two groups, there was significant difference in m I/Cr(left P=0.015, right P=0.011), and NAA/m I ratios(left P=0.044, right P=0.031), and there was significant difference in NAA/Cr among the two groups in the left hippocampus(P=0.034), however there were no significant difference in NAA/Cr in the right hippocampus among the two groups(P=0.505). There was also no significant difference in Cho/Cr ratio among the two groups(left P=0.226, right P=0.688).3. We compared the metabolism ratios in the bilateral hippocampus of the AD patients and found the NAA/Cr and m I/Cr in the left hippocampus were lower than the right one(P=0.029,0.021), whereas we found no significant difference in the ratios of NAA/Cr and Cho/Cr between the bilateral hippocampus(P =0.406,0.732).4. In AD patients the ratios of m I/Cr in the left hippocampus had negative correlations with the scores of MMSE and Mo CA(rs=-0.349,P=0.042;rs=-0.427,P=0.021), and positive correlation with the scores of ADL(rs=0.472, P=0.01). However,NAA/m I in left hippocampus had the opposite results(rs=0.209,P=0.028;rs=0.251,P=0.018; rs=-0.385,P=0.039). The ratios of NAA/Cr and Cho/Cr in the bilateral hippocampus, and m I/Cr, NAA/m I of the right hippocampus had no significant correlations with the scores of MMSE, Mo CA and ADL(All P>0.05).Conclusion1.Using MMSE and Mo CA can well evaluate the cognitive level of AD patients. ADL scores can reflect the abilities of daily life in AD patients.2.We can detect the information of the brain metabolites changes in cellular level non-invasively through 1H MRS, which can help us understand the pathophysiological process of disease; AD patients has lower NAA/m I and higher m I/Cr in comparison with the normal controls, and there were more changes in the left hippocampus than the right one in AD patients, which has obvious correlations with MMSE、Mo CA and ADL scores. So we infer the ratios of NAA/m I and m I/Cr may be sensitive indexes of reflexing the hippocampus metabolites changes, which is important to the early diagnosis and the pathogenesis detection of AD.