Evidence for cortical "disconnection" as a mechanism of age-related cognitive decline
Evidence for cortical "disconnection" as a mechanism of age-related cognitive decline
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DOI：
10.1212/wnl.57.4.632
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发表时间：
2001-08-28
期刊：
影响因子：
9.9
通讯作者：
Markus, HS
中科院分区：
文献类型：
--
作者：
O'Sullivan, M;Jones, DK;Markus, HS
背景资料：正常的衰老伴随着认知能力的下降，执行能力可能会受到选择性的影响，但潜在的机制仍然不清楚，缺乏预防策略。有人认为，由于白色纤维的损失，皮质“断开”可能发挥了重要作用。但是，到目前为止，还没有直接证明人体体内的结构断开。研究方法：作者使用扩散张量MRI寻找20名常规MRI扫描正常的老年志愿者和10名年轻对照组大脑白色物质超微结构变化的证据。老年组还接受了神经心理学评估。结果如下：扩散各向异性，白色物质道完整性的标志，在老年受试者的白色物质中减少，并随着年龄的增加而线性下降。老年组的平均扩散率较高，并随着年龄的增长而增加。这些变化在前部白色物质中最大。在老年组，前平均扩散与执行功能的连线测试评估。结论：这些发现提供了直接的证据表明，白色物质束破坏发生在正常老化，并将与年龄相关的认知能力下降的皮层断开假说相一致。前部白色物质的最大变化为执行功能的选择性丧失提供了合理的结构基础。除了提供有关认知能力生物学基础的新信息外，弥散张量MRI可能是评估旨在预防认知能力下降的干预措施的敏感工具。
Background: Normal aging is accompanied by a decline of cognitive abilities, and executive skills may be affected selectively, but the underlying mechanisms remain obscure and preventive strategies are lacking. It has been suggested that cortical "disconnection" due to the loss of white matter fibers may play an important role. But, to date, there has been no direct demonstration of structural disconnection in humans in vivo. Methods: The authors used diffusion tensor MRI to look for evidence of ultrastructural changes in cerebral white matter in a group of 20 elderly volunteers with normal conventional MRI scans, and a group of 10 younger controls. The older group also underwent neuropsychological assessment. Results: Diffusional anisotropy, a marker of white matter tract integrity, was reduced in the white matter of older subjects and fell linearly with increasing age in the older group. Mean diffusivity was higher in the older group and increased with age. These changes were maximal in anterior white matter. In the older group, anterior mean diffusivity correlated with executive function assessed by the Trail Making Test. Conclusions: These findings provide direct evidence that white matter tract disruption occurs in normal aging and would be consistent with the cortical disconnection hypothesis of age-related cognitive decline. Maximal changes in anterior white matter provide a plausible structural basis for selective loss of executive functions. In addition to providing new information about the biological basis of cognitive abilities, diffusion tensor MRI may be a sensitive tool for assessing interventions aimed at preventing cognitive decline.