Your Brain Remembers Illness

A friend calls with the news she was just diagnosed with COVID-19. You had dinner with her last night, and suddenly you start coughing, feel flu-like symptoms, and your fever spikes. What’s going on? Are you coming down with the virus or are your symptoms psychosomatic?

You test negative. Yet Technion Associate Professor Asya Rolls (opens in a new tab) wonders — can the brain induce an actual disease?

In a recent study involving mice published in Cell, Prof. Rolls and a team of researchers showed that not only can the brain make the body sick, but just as the brain remembers people, places, and smells, it stores “memory traces” of the illness. Moreover, reactivating that memory is enough to reawaken past immune system responses.

Prof. Rolls and M.D./Ph.D. student Tamar Cohen, with scientists from the University of Haifa and EMMS Hospital in Nazereth, first induced colitis, or inflammation of the colon, in laboratory mice. They found that brain cells became active in several regions, including the insular cortex, responsible for sensory perceptions. The team waited for the mice to recover and then injected them with a drug that artificially reactivated the insular cortex brain cells. Sure enough, inflammation re-emerged in the exact same location even though there was no infection, demonstrating that the brain remembered the infection and told the immune system to fight.

“I was surprised to see the effect so clearly, with inflammation starting soon after neurons were activated, even though there was no pathogen or other physical trigger,” said Rolls.