The developing brain is constantly forming new connections, or synapses, between nerve cells. Many connections are eventually lost, while others are strengthened. In 2012, Beth Stevens, PhD and her lab at Boston Children’s Hospital showed that microglia, immune cells that live in the brain, prune back unwanted synapses by engulfing or “eating” them. They also identified a set of “eat me” signals required to promote this process: complement proteins, best known for helping the immune system combat infection.
Currently, there are five FDA-approved drugs for Alzheimer’s disease, but these only boost cognition temporarily and don’t address the root causes of Alzheimer’s dementia. Many newer drugs in the pipeline seek to eliminate amyloid plaque deposits or reduce inflammation in the brain, but by the time this pathology is detectable, it’s unlikely medications can do much to slow the disease.