Hedden Trey, Gabrieli John D E
Stanford University, Stanford, California, Cambridge, Massachusetts, USA.
Curr Opin Neurol. 2005 Dec;18(6):740-7. doi: 10.1097/01.wco.0000189875.29852.48.
Recent research has revealed that the population of older adults is composed not only of individuals who are either healthy or have an age-related disease, most commonly Alzheimer's disease, but also individuals with mild cognitive impairment who are at-risk for or already in the prodromal stage of Alzheimer's disease. These variations in cognitive aging can be related to their neural bases via structural and functional neuroimaging methods.
Healthy aging appears to primarily affect a frontal-striatal system that undergirds executive control of cognition, while minimally affecting medial temporal lobe structures. Functional imaging studies suggest that enhanced prefrontal engagement may offer compensatory plasticity that minimizes age-related cognitive losses. Mild cognitive impairment appears to affect the entorhinal cortex in particular, with functional consequences in other brain regions. Alzheimer's disease is characterized by severe hippocampal injury, although early-stage Alzheimer's disease may relatively spare some cortical regions.
Advances in in-vivo imaging methods are providing the tools for identifying different trajectories of neurocognitive aging, and knowledge about these brain changes may promote opportunities for treatment.
最近的研究表明，老年人群不仅包括健康个体或患有与年龄相关疾病（最常见的是阿尔茨海默病）的个体，还包括有轻度认知障碍的个体，这些个体处于阿尔茨海默病的风险期或已经处于前驱期。通过结构和功能神经影像学方法，认知衰老的这些差异可能与其神经基础相关。
健康衰老似乎主要影响支持认知执行控制的额叶 - 纹状体系统，而对内侧颞叶结构的影响最小。功能成像研究表明，增强的前额叶参与可能提供补偿性可塑性，从而将与年龄相关的认知损失降至最低。轻度认知障碍似乎特别影响内嗅皮质，并在其他脑区产生功能后果。阿尔茨海默病的特征是严重的海马损伤，尽管早期阿尔茨海默病可能相对 spared 一些皮质区域。
体内成像方法的进展为识别神经认知衰老的不同轨迹提供了工具，而关于这些脑变化的知识可能会促进治疗机会。
