Abstract
Microglia play a curious role in the nervous system. Their role is intrinsically protective and supportive, but during neurodegenerative disease, it is well established that microglia play a significant role in the initiation of neuronal death. Microglia, like neurons, show age-related changes that could potentially alter their behavior. While extreme changes to a large population of microglia cause dramatic neuronal loss in neurodegeneration, during normal aging, subtle changes not unlike those seen in the disease state could potentially contribute to a more gradual neuronal loss that could contribute to the cognitive decline seen in the aging population. This review provides illustrations of what is known about the role of microglia in neurodegeneration and makes suggestions about the role of microglia in age-related changes to the brain.