Can our brain talk to our immune system?

A 2025 study of 250 people found that the brain can tell the immune system to prepare for impending infection even before a microbe enters the body. Scientists asked volunteers to don virtual reality headsets that showed various virtual people approaching them. Some of those approaching appeared to be healthy and others appeared to be sick. Brain scans and blood tests showed that participants’ brains activated their immune systems when a virtual sick person simply came near them.