Mielke R, Kessler J, Szelies B, Herholz K, Wienhard K, Heiss W D
Max-Planck-Institut für neurologische Forschung and Universitätsklinik für Neurologie, Köln, Federal Republic of Germany.
J Neural Transm (Vienna). 1998;105(8-9):821-37. doi: 10.1007/s007020050097.
Normal aging of the brain is predominantly characterized by metabolic changes in the prefrontal cortex. While in middle age there is a trend to hyperfrontality, PET demonstrates in old age a decline of regional cerebral glucose metabolism in frontal areas. In progeric diseases, clinically apparent as premature aging, the metabolic pattern is similar like in normal aging but qualitatively more severe. In patients with the diagnosis of probable Alzheimer's disease (AD) hypometabolism in early dementia is typically present in heteromodal association areas. Hypometabolism then spreads to other cortical and subcortical regions suggesting a characteristic pattern of degeneration that reflects selective vulnerability within limbic-cortical networks. Synaptic plasticity, clinically apparent as cognitive reserve capacity, can be assessed by PET under specific cognitive activation. In AD it is reduced in comparison to age-matched normals and may be influenced by drugs giving trophic support to neurochemical systems.
大脑的正常老化主要表现为前额叶皮质的代谢变化。中年时存在额叶功能亢进的趋势，而正电子发射断层扫描（PET）显示，老年时额叶区域的脑葡萄糖代谢会下降。在早衰性疾病中，临床表现为过早衰老，其代谢模式与正常老化相似，但在程度上更为严重。在被诊断为可能患有阿尔茨海默病（AD）的患者中，早期痴呆时的代谢减低通常出现在异模态联合区。随后，代谢减低会扩散到其他皮质和皮质下区域，提示一种特征性的退化模式，反映了边缘-皮质网络内的选择性易损性。突触可塑性，临床表现为认知储备能力，可在特定认知激活下通过PET进行评估。与年龄匹配的正常人相比，AD患者的突触可塑性降低，并且可能受到为神经化学系统提供营养支持的药物的影响。
