[Age-related brain functional changes and microglia].

Abstract

Age-related alterations in brain function are considered a physiological phenomenon that everyone may experience as a decline in memory and cognitive abilities. However, the rate of progression varies among individuals, and the underlying mechanisms remain largely unclear. Microglia, the resident immune cells of the brain, play a crucial role in maintaining central nervous system homeostasis through diverse functions such as phagocytosis of cellular debris, synaptic pruning, and regulation of neuroinflammatory responses. Previous studies have demonstrated that the cellular morphology of microglia undergoes significant changes with age. Furthermore, recent advances in RNA sequencing analysis techniques have revealed that microglia are not a homogeneous cell population but rather consist of diverse subpopulations. Notably, white matter-associated microglia (WAM) and interferon-response microglia (IRM) are reported to increase in proportion with aging. Thus, aging induces complex changes in the morphology, function, and subpopulation composition of microglia, which may impair the homeostatic maintenance of brain and contribute to age-related alterations in brain function, such as cognitive decline. This review focuses on the impact of aging on microglia and their association with changes in brain function, presenting the latest findings in this field.