Glutamate (Glu) is a key molecule in cellular metabolism, the most abundant excitatory neurotransmitter in the brain, and the principal neurotransmitter of cortical efferents. Glutamate dysfunction, on the other hand, is common in neurodegenerative disorders, and likely contributes to age-related declines in behavioral and cognitive functioning. Nonetheless, the extant literature measuring age-related changes in brain glutamate in vivo has yet to be comprehensively and quantitatively summarized. This meta-analysis examines proton spectroscopy (1HMRS) measures of Glu-related brain metabolites across 589 healthy young and older adults. Glu (Cohen's d = -0.82) and Glu+glutamine (Cohen's d = -0.51) concentrations were significantly lower in older compared with younger adults, whereas the concentration of glutamine (d = 0.43) was significantly higher in older individuals. Notably, 1HMRS methodological choices impacted effect sizes for age-related Glu differences. Glu metabolite change appears to be a robust marker of aging-related neurological change; however, additional studies are needed to elucidate age-related trajectories of glutamatergic alterations and their relationship to cognitive phenotypes.

中文翻译：

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衰老过程中脑谷氨酸代谢物的定量 Meta 分析

谷氨酸 (Glu) 是细胞代谢的关键分子，是大脑中含量最丰富的兴奋性神经递质，也是皮层传出的主要神经递质。另一方面，谷氨酸功能障碍在神经退行性疾病中很常见，并且可能导致与年龄相关的行为和认知功能下降。尽管如此，测量体内脑谷氨酸与年龄相关变化的现有文献尚未得到全面和定量的总结。这项荟萃分析检查了 589 名健康的年轻人和老年人的 Glu 相关脑代谢物的质子光谱 (1HMRS) 测量。与年轻人相比，老年人的 Glu（Cohen's d = -0.82）和 Glu+谷氨酰胺（Cohen's d = -0.51）浓度显着较低，而谷氨酰胺（d = 0. 43) 在老年人中显着更高。值得注意的是，1HMRS 方法选择影响了与年龄相关的 Glu 差异的效应大小。Glu 代谢物的变化似乎是与衰老相关的神经系统变化的有力标志；然而，需要更多的研究来阐明与年龄相关的谷氨酸能改变轨迹及其与认知表型的关系。