Microglia in brain aging

The process of aging is characterized by the progressive degeneration of tissues and organs, resulting in a higher mortality rate. The brain is one of the most affected organs. Age-related brain changes include the abnormal neuronal activity, calcium homeostasis dysfunction, dysregulation of mitochondrial function, and reactive oxygen species (ROS), finally all contributing to cognitive deterioration. Aging is also one of the main risk factors for the development of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, etc. For many years, neurodegenerative disease research was concentrated primarily on neurons, with microglia receiving significantly less attention. Recently, microglial homeostasis has emerged as an important mediator in the pathogenesis of neurological diseases. To facilitate an overview of the current knowledge, here we look at brain aging from the microglia’s perspective， present the current state of knowledge on the relationship of brain aging and the microglia. We summarize the recent progress of research about microglia in normal aging, Alzheimer's disease(AD), Parkinson's disease(PD), Huntington's disease(HD), and amyotrophic lateral sclerosis(ALS), then discuss the relationship between senescent microglia and brain aging. Understanding the molecular complexity of the microglia in brain aging will suggest new avenues for healthy aging.