Morphological changes in nerve cells during normal aging

Abstract

During normal aging, widespread loss of nerve cells does not occur. Neuronal loss is limited to restricted regions of the nervous system and is slight (probably no more than 10%). The commonest age-related structural changes undergone by nerve cells are as follows: dendrites decrease in number and length and many dendritic spines are lost; axons decrease in number and their myelin sheaths may become less compact and undergo segmental demyelination followed by remyelination; and significant loss of synapses occurs. These changes probably make a significant contribution to the behavioral impairment and cognitive decline that often accompany normal aging.

Increased electrical nerve stimulation threshold of the sciatic nerve in patients with diabetic foot gangrene

“…Mechanisms such as the degeneration of axons and alterations in the myelin sheaths occur in aging patients. 37 The amplitude of the compound muscle action potentials of the tibial nerve decrease markedly with age. 38 Inflammatory cascades, which may have been induced in our patients with diabetic gangrene, additionally contribute to the damage of nerve 438 Keyl et al axons.…”

Age-related microstructural differences quantified using myelin water imaging and advanced diffusion MRI

“…Throughout adulthood, the human brain undergoes significant biophysical changes in both white matter (WM) and gray matter (GM) (Pannese, 2011). In contrast to nonhuman primates, these maturating and regressive processes occur heterochronically in different brain regions (Haroutunian et al, 2014).…”

Aging somatosensory cortex displays increased density of WFA-binding perineuronal nets associated with GAD-negative neurons

“…The mechanisms of this phenomenon have been extensively studied (for review, see Burke and Barnes, 2006); however, no consensus view has yet been elaborated. Hypotheses concerning morphological changes across various brain areas have emerged, and age-associated deficits were for a long time attributed to decreases in total neuron number or in the number of specific neuron classes (for review see Pannese, 2011). Newer research, however, has provided widely accepted evidence that the number of neurons in many brain areas is preserved across aging (Rapp and Gallagher, 1996;Rasmussen et al, 1996;Merrill et al, 2001).…”