Abstract: Objective To evaluate the metabolism change with aging brain in the different regions of the bilateral hippocampal using 1 H magnetic resonance spectroscopy(1 H-MRS),and to further investigate the correlation between metabolites,metabolite concentrations ratio and age. Methods Brain conventional MRI,MRS were employed in 121 right-handed healthy volunteers. After selecting the regions of interest artificially,the required parameters N-acetyl-aspartate (NAA),choline compounds(Cho),creatine(Cr)were measured by the machine automatically.The parameters between genders and ages were compared.Pearson correlation analysis was used to further investigate the correlation between the concentrations of NAA,Cho,Cr and age in different regions of the hippocampus.Results No significant gender effects were found in the concentrations of NAA,Cho,Cr(P >0.05 ).A significant age effects were found in the concentrations of NAA in the hippocampal head,body(body 1 area,body 2 area)and tail.The concentrations of NAA in the above regions of elderly group decreased significantly as compared with young and elderly group(P <0.05),while NAA showed significant changes between young and middle aged group in the hippocampal head,body(body 1 area,body 2 area)and tail(P >0.05 ).No significant age-associated changes were observed in Cho,Cr.Only the NAA concentrations were negatively correlated with age in bilateral hippocampal head,body(body 1 area,2 area),and tail(P <0.05).No significant age-associated changes were observed in Cho,Cr (P >0.05).Conclusion The NAA concentration decreased with age in the different regions of the hippocampus during normal brain aging.The NAA concentration in elderly group is significantly lower than that of young and middle aged group.No significant differences are found in the concentrations of NAA,Cho,Cr between genders.

Key words: proton magnetic resonance spectroscopy, hippocampus, brain aging, correlation analysis