Marked loss of myelinated nerve fibers in the human brain with age
Marked loss of myelinated nerve fibers in the human brain with age
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DOI：
10.1002/cne.10714
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发表时间：
2003-07-21
影响因子：
2.5
通讯作者：
Pakkenberg, B
中科院分区：
文献类型：
--
作者：
Marner, L;Nyengaard, JR;Pakkenberg, B
大脑中的白色物质随着年龄的增长而减少的最多，几乎减少了30%，但是对于构成白色物质的纤维的年龄效应却知之甚少。本研究应用体视学方法测量了有髓神经纤维的总长度。样本来自36名正常丹麦人（18名男性和18名女性），年龄范围在18至93岁之间。从白色物质中系统随机取样，切片前随机旋转活检标本，以避免由于神经纤维的各向异性性质而产生的偏倚。在光学显微镜水平下以约10，000 X放大倍数对纤维进行计数，并测量每个计数纤维的直径以获得直径分布。男性在20岁时的有髓纤维总长度为176，000 km，80岁时为97，200 km，而女性在20岁时的总长度为149，000 km，80岁时为82，000 km。这一发现相当于每十年下降10%，或从20岁到80岁总共下降45%，性别差异为16%。纤维直径分布表明，主要是较细的纤维损失与较厚的相对保存。随着年龄的增长，有髓神经纤维的明显损失可以解释老年人的认知能力下降。
The white matter is the structure of the brain that declines most with age-almost 30%, but little is known about the age-effect on the fibers that constitute the white matter. In the present study, the total length of myelinated fibers was measured with a newly developed stereologic method. Specimens came from 36 normal Danes (18 males and 18 females) with an age ranging between 18 and 93 years. Samples were taken systematically and randomly from the white matter, and the biopsy specimens were randomly rotated before sectioning to avoid bias due to the anisotropic nature of nerve fibers. The fibers were counted at light microscopic level at approximately 10,000X magnification, and the diameter of each counted fiber was measured to get the diameter distribution. Males were found to have a total myelinated fiber length of 176,000 km at the age of 20 and 97,200 km at the age of 80, whereas the total length in females was 149,000 kin at the age of 20 and 82,000 km at the age of 80. This finding corresponds to a 10% decrease per decade or a total decrease of 45% from the age of 20 to 80 years, and a sex difference of 16%. The fiber diameter distribution showed that primarily the thinner fibers were lost with a relative preservation of the thicker ones. The marked loss of myelinated nerve fibers with age could explain some of the cognitive decline seen in the elderly.