August 06, 2025
A new study suggests that simply seeing someone who looks sick can trigger the body’s immune system — almost as if an infection were already underway. Researchers found that the brain activates key immune cells in response to visual cues of illness, essentially priming the body’s defenses before any real exposure occurs.
To test this, scientists at the University Hospital of Lausanne in Switzerland used an unusual setup. Volunteers wore virtual reality headsets and encountered digital avatars showing symptoms like coughing or skin rashes. By using avatars instead of real patients, the team avoided exposing participants to dangerous pathogens while still simulating the presence of illness.
Brain scans and blood tests revealed that participants’ immune systems responded to the sick-looking avatars in much the same way they would to an actual infection. “It shows the brain’s remarkable ability to predict what’s happening and prepare the body to respond,” said study co-author Andrea Serino, a neuroscientist at Lausanne.
The findings, published in Nature Neuroscience on July 28, highlight how perception alone can mobilize the immune system. This rapid, preemptive response could help the body act more quickly in real-world situations where infection is possible.
SOURCE: https://www.scientificamerican.com/article/brains-react-to-signs-of-illness-even-when-its-not-real/