Aim of the study: Cognitive decline due to aging is most probably the result of changes in the white matter in the central nervous system (CNS) and/or demyelination.
Material and methods: We used electron microscopic analysis of the morphological changes in aging rats' optic nerves as an easily accessible part of the CNS.
Results: Several age changes were observed in aging rats (36 months) vs. young adult rats (6 months), namely degeneration of axons, decreased packing density and morphological alterations of myelination, including the ballooning of some myelin sheaths, separation of myelin lamellae and degenerative changes in the oligodendrocytes population.
Conclusion: Cognitive decline related to aging may occur in part due to the disturbed myelination of axons in CNS white matter.
Keywords: Optic nerve; aging; diabetes mellitus; myelin; white matter.