We have some medicines and therapies that can help kill a viral infection, but nothing as powerful as what the healthy body can do on its own. An immune system that’s working well can overcome an infection and even sometimes prevent reinfection.

But our immune systems do more than kill viruses. In fact, your brain has its own immune system for clearing away toxins that prevent your neurons from communicating properly with each other. Your brain produces special cells that act as trash collectors to clean up these toxins. These cells are called microglia, and they’re macrophages: cells that engulf and break down toxic debris. Microglia are your brain’s first line of defense against amyloid plaques that can accumulate between the neurons and disrupt their functioning.

Potentially life-changing research is focusing on microglia and how they are activated and mobilized to do their vital work. Researchers have known for some time that a healthy brain produces waves at a certain frequency (40Hz per second) and that this rhythm is disrupted in the brains of people with Alzheimer’s disease.

In 2016, researchers from MIT found that exposing mice to lights that flicker at this same frequency—40 flickers per second—could actually reduce the build-up of the brain-disrupting plaque that is thought to cause dementia in people with Alzheimer’s disease. New research, building on that breakthrough study, has discovered more about the mechanism behind this surprising effect. The flickering light, tuned to the brain’s natural rhythm, increases the expression of cytokines, a special chemical whose job it is to recruit microglia to break down the toxic plaques.

Notice that this research is focused on understanding how the healthy brain works. The flickering lights in both studies are designed not to target the toxic amyloid plaque directly, but to encourage the brain to use its own system more efficiently. The light serves to boost the health of the brain—not to interfere with or replace the brain’s natural functions.