Structural Brain Changes in Aging: Courses, Causes and Cognitive Consequences
Structural Brain Changes in Aging: Courses, Causes and Cognitive Consequences
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DOI：
10.1515/revneuro.2010.21.3.187
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发表时间：
2010-01-01
影响因子：
4.1
通讯作者：
Walhovd, Kristine B.
中科院分区：
文献类型：
--
作者：
Fjell, Anders M.;Walhovd, Kristine B.
大脑的结构从出生到一生都在不断变化，这意味着正常的衰老，没有痴呆症，与大脑结构的变化有关。本文回顾了最近的证据，磁共振成像（MRI）研究有关年龄相关的变化，在大脑中。主要结论是：（1）健康老年人脑体积缩小，脑室系统扩张。然而，变化的模式是高度异质性的，最大的变化见于额叶和颞叶皮层，以及壳核、丘脑和丘脑。利用现代MRI数据分析方法，可以在短至一年的时间内跟踪皮质厚度和皮质下体积的变化，大多数大脑区域的年减少率在0.5%至1.0%之间。(2)健康老龄化中的脑体积减少可能仅在较小程度上与神经元损失相关。相反，神经元的萎缩、突触棘的减少和突触数量的减少可能是灰质减少的原因。此外，有髓轴突的长度大大减少，高达近50%。(3)特定认知能力的下降，例如处理速度、执行功能和情景记忆，在健康的老龄化中可以看到。这种减少在很大程度上是由神经解剖学的变化介导的，这意味着年轻人和老年人在选定的认知功能方面的差异有25%到100%可以用大脑结构特征的群体差异来解释。
The structure of the brain is constantly changing from birth throughout the lifetime, meaning that normal aging, free from dementia, is associated with structural brain changes. This paper reviews recent evidence from magnetic resonance imaging (MRI) studies about age-related changes in the brain. The main conclusions are that (1) the brain shrinks in volume and the ventricular system expands in healthy aging. However, the pattern of changes is highly heterogeneous, with the largest changes seen in the frontal and temporal cortex, and in the putamen, thalamus, and accumbens. With modern approaches to analysis of MRI data, changes in cortical thickness and subcortical volume can be tracked over periods as short as one year, with annual reductions of between 0.5% and 1.0% in most brain areas. (2) The volumetric brain reductions in healthy aging are likely only to a minor extent related to neuronal loss. Rather, shrinkage of neurons, reductions of synaptic spines, and lower numbers of synapses probably account for the reductions in grey matter. In addition, the length of myelinated axons is greatly reduced, up to almost 50%. (3) Reductions in specific cognitive abilities-for instance processing speed, executive functions, and episodic memory-are seen in healthy aging. Such reductions are to a substantial degree mediated by neuroanatomical changes, meaning that between 25% and 100% of the differences between young and old participants in selected cognitive functions can be explained by group differences in structural brain characteristics.