Marked loss of myelinated nerve fibers in the human brain with age

  title={Marked loss of myelinated nerve fibers in the human brain with age},
  author={Lisbeth Marner and Jens Randel Nyengaard and Yong Tang and Bente Pakkenberg},
  journal={Journal of Comparative Neurology},
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… 
Aging of bovine spinal cord: an alteration of myelinated nerve fibers in the white matter
  • S. Ohfuji
  • Biology
    Comparative Clinical Pathology
  • 2019
The changes observed in the spinal cord white matter of the present cows were similar to those described previously in aged human beings and domestic and laboratory animals, and thus were likely to have been a phenomenon which was closely related to aging.
How the primate fornix is affected by age
The effects of age on nerve fibers and neuroglial cells in the fornix were examined in 25 rhesus monkeys between 4 and 33 years of age and it is suggested that these correlations result from some disconnection of the hippocampus from the thalamus, septal nuclei, and medial frontal cortex.
Demyelination Induces the Decline of the Myelinated Fiber Length in Aged Rat White Matter
It is suggested that demyelination of myelinated fibers with small diameters in aged white matter might be the key mechanism of the significant decline of the myelination fiber length in agedwhite matter.
The results were satisfactory in the sense that the sampling variance introduced by the stereological estimation procedure was a minor fraction of the observed variance and the comparison of the white matter and the myelinated fibers in thewhite matter between rat brain and human brain was also made.
Stereological estimation of the total number of myelinated callosal fibers in human subjects
It is suggested that many mechanisms are involved in the development and determination of axonal projections across the CC that cannot simply be explained by the neocortical neuron number.
The myelinated fiber changes in the white matter of aged female Long‐Evans rats
Age‐related changes of the white matter and the myelinated fibers in white matter of female Long‐Evans rats were investigated by the use of design‐based stereological methods and indicated that the age‐related loss of theMyelinated fiber length in thewhite matter of aged rats was mainly as a result of the marked loss ofthe myelination fibers with smaller diameter.
The Effects of Normal Aging on Myelinated Nerve Fibers in Monkey Central Nervous System
The degeneration of other myelin sheaths and the subsequent remyelination of axons by shorter internodes slow down the rate conduction along nerve fibers, which affects the integrity and timing in neuronal circuits, and there is evidence that they contribute to cognitive decline.


Age‐Related White Matter Atrophy in the Human Brain
The findings show that the age-related decline in brain volume is much more a question of white matter atrophy than of brain cortex atrophy, which could be an indirect indicator of nerve cell loss, since the volume of a nerve cell is much smaller than its myelinated fiber.
A stereological method for estimating the total length and size of myelin fibers in human brain white matter
Effects of age on the thickness of myelin sheaths in monkey primary visual cortex
It seems that, with age, there is some degeneration of myelin but, at the same time, a continued production of lamellae in the myelin sheaths of old monkeys.
Effects of aging on myelinated nerve fibers in monkey primary visual cortex
In monkeys, myelin sheaths of the axons in the vertical bundles of nerve fibers passing through the deeper layers of primary visual cortex show age‐related alterations in their structure, and there is a significant correlation between the breakdown of the myelin and the impairments in cognition exhibited by individual monkeys.
Effects of age on tissues and regions of the cerebrum and cerebellum
Neocortical neuron number in humans: Effect of sex and age
Sex and age were the main determinants of the total number of neurons in the human neocortex, whereas body size, per se, had no influence on neuron number.
Age Dependent White Matter Lesions and Brain Volume Changes in Healthy Volunteers
The results suggest that with aging central atrophy increases more (relatively) than cortical atrophy.
Age‐related changes in oligodendrocytes in monkey cerebral cortex
  • A. Peters
  • Biology
    The Journal of comparative neurology
  • 1996
It is hypothesized that the alterations in the oligodendrocyte‐myelin system lead to changes in the rates of conduction along fibers whose myelin sheaths are affected, and this may be one of the causes of the behavioral changes associated with aging in primates.
White matter changes with normal aging
The finding of a highly significant decrease with age in white matter, in the absence of a substantial decrease in gray matter, is consistent with recent neuropathologic reports in humans and nonhuman primates.