In recent years, increasing attention has been given to the role of unresolved, chronic inflammation in the development of neurodegenerative disease. Normal tissue maintenance requires the involvement of immune cells, and inflammatory signaling is disruptive to that process. In the brain, immune cells take on a greater range of tasks than is the case elsewhere, becoming involved in maintenance of synaptic connections between neurons, for example. That too is disrupted by inflammatory signaling that changes the behavior of these cells. Chronic inflammation in the absence of the usual causes, pathogens and injury, is a feature of aging. Researchers are investigating the causes of inflammation and mechanisms of regulation of inflammation in search of ways to damp down the inappropriate excessive inflammatory signaling of aging without also suppressing the necessary inflammation required for a robust immune defense. Some of the causes…