Brain aging is a complicated and diversified process that includes an ongoing decline in cognitive performance as well as various cellular and molecular changes in the brain. During an individual's life, glial cells such as oligodendrocytes, microglia, and astrocytes are crucial for maintaining healthy brain function. Astrocytes support neurons but may become less efficient with age, contributing to cognitive decline. Microglia, the brain's immune cells, can turn overactive with age, causing inflammation which can lead to neuronal damage. Oligodendrocytes, responsible for myelin sheath maintenance, also undergo changes, affecting neural communication. With advancing age, changes in glial cell function may lead to neuroinflammation, oxidative damage, and abnormalities in neural circuitry, all of which contribute to age related cognitive decline and neurodegenerative disorders. This chapter delves into the intricate dynamics of brain aging, focusing on the profound influence of age-related changes in glial cells.
Top1. Introduction
Brain aging is characterized by a multitude of dynamic changes in glial cells, particularly astrocytes (Palmer and Ousman, 2018) and microglia (von Bernhardi, Eugenín-von Bernhardi, and Eugenín, 2015), which have far-reaching implications for neural function and age-related neurodegenerative diseases (Suksuphew and Noisa, 2015). Astrocytes, until thought to be inert supporters, reveal an unseen dynamism as they age (Matias, Morgado, and Gomes, 2019). Their cellular hypertrophy, the swelling of cell bodies and processes, and the reconfiguration of their structural components paint a vivid portrait of their evolution (Verkhratsky et al., 2019; Clarke et al., 2018; Stogsdill et al., 2017). In turn, microglia, the brain's vigilant sentinels, metamorphose in response to neuroinflammatory cues or cellular distress (Muzio, Viotti, and Martino, 2021). They transition from a state of constant surveillance, characterized by long, branched processes, to an activated, amoeboid form replete with pro-inflammatory attributes (Hickman et al., 2013).
This change brings about long-lasting inflammation in the brain, which is a common sign of brain aging. It may significantly affect cognitive performance and potentially cause neurodegenerative diseases (Jin et al., 2022). These changes in the shape of glial cells with the age course suggests that the aging brain is always changing, and this can affect the complex functioning of the brain.
This chapter explores the changing role of glial cells in the aging brain, exploring their morphological and functional changes. As well, it examines how these changes impact brain function, including synaptic activity, neurotransmitter regulation, and susceptibility to oxidative stress. Additionally, it highlights the glial cell contributions to age-related neurodegenerative diseases like Alzheimer's, Parkinson's, and multiple sclerosis, underscoring the significance of aging in these conditions.
Additionally, it investigates the delicate interplay of oxidative stress, inflammation, genetics and epigenetics, to understand the mechanisms causing these changes in order to figure out the mysteries of brain aging, enabling the development of new strategies for preserving the healthy aging and combatting age-related neurological disorders.