Research Center on Aging, Departments of Physiology and Biophysics,
Research Center on Aging, Medicine.
Am J Physiol Endocrinol Metab. 2014 Jun 1;306(11):E1315-21. doi: 10.1152/ajpendo.00067.2014. Epub 2014 Apr 15.
Several studies have suggested that glucose hypometabolism may be present in specific brain regions in cognitively normal older adults and could contribute to the risk of subsequent cognitive decline. However, certain methodological shortcomings, including a lack of partial volume effect (PVE) correction or insufficient cognitive testing, confound the interpretation of most studies on this topic. We combined [(18)F]fluorodeoxyglucose ([(18)F]FDG) positron emission tomography (PET) and magnetic resonance (MR) imaging to quantify cerebral metabolic rate of glucose (CMRg) as well as cortical volume and thickness in 43 anatomically defined brain regions from a group of cognitively normal younger (25 ± 3 yr old; n = 25) and older adults (71 ± 9 yr old; n = 31). After correcting for PVE, we observed 11-17% lower CMRg in three specific brain regions of the older group: the superior frontal cortex, the caudal middle frontal cortex, and the caudate (P ≤ 0.01 false discovery rate-corrected). In the older group, cortical volumes and cortical thickness were 13-33 and 7-18% lower, respectively, in multiple brain regions (P ≤ 0.01 FDR correction). There were no differences in CMRg between individuals who were or were not prescribed antihypertensive medication. There were no significant correlations between CMRg and cognitive performance or metabolic parameters measured in fasting plasma. We conclude that highly localized glucose hypometabolism and widespread cortical thinning and atrophy can be present in older adults who are cognitively normal, as assessed using age-normed neuropsychological testing measures.
几项研究表明，葡萄糖代谢低下可能存在于认知正常的老年人大脑中的特定区域，并可能导致随后认知能力下降的风险增加。然而，某些方法学上的缺陷，包括缺乏部分容积效应（PVE）校正或认知测试不足，混淆了大多数关于该主题的研究的解释。我们结合了[(18)F]氟代脱氧葡萄糖([(18)F]FDG)正电子发射断层扫描（PET）和磁共振（MR）成像，以定量测量一组认知正常的年轻（25 ± 3 岁；n = 25）和老年（71 ± 9 岁；n = 31）个体的 43 个解剖定义的脑区的脑葡萄糖代谢率（CMRg）以及皮质体积和厚度。在对 PVE 进行校正后，我们在老年组的三个特定脑区观察到 11-17%的 CMRg 降低：额上回、中额下回和尾状核（P ≤ 0.01 假发现率校正）。在老年组中，多个脑区的皮质体积和皮质厚度分别降低了 13-33%和 7-18%（P ≤ 0.01 FDR 校正）。服用或未服用抗高血压药物的个体之间的 CMRg 没有差异。CMRg 与空腹血浆中测量的认知表现或代谢参数之间没有显著相关性。我们的结论是，使用年龄标准化的神经心理学测试措施评估，认知正常的老年人可能存在高度局部的葡萄糖代谢低下以及广泛的皮质变薄和萎缩。
