The brain detects disease in others even before it breaks out

By Arif Kisana

STOCKHOLM: The human brain is much better than previously thought at discovering and avoiding disease, a new study led by researchers at Karolinska Institute in Sweden reports. Our sense of vision and smell alone are enough to make us aware that someone has a disease even before it breaks out. And not only aware, we also act upon the information and avoid sick people. The human immune system is effective at combating disease, but since it entails a great deal of energy expenditure disease avoidance should be part of our survival instinct. A new study now shows that this is indeed the case. The human brain is better than previously thought at discovering early-stage disease in others. Moreover, we also have a tendency to act upon the signals by liking infected people less than healthy ones.

“The study shows us that the human brain is actually very good at discovering this and that this discovery motivates avoidance behavior,” says principal investigator Professor Mats Olsson at Karolinska Institute.

“Common sense tells us that there should be a basic behavioral repertoire that assists the immune system. Avoidance, however, does not necessarily apply if you have a close relationship with the person who is ill,” says Professor Olsson. “For instance, there are few people other than your children who you’d kiss when they have a runny nose. In other words, a disease signal can enhance caring behavior in close relationships. With this study, we demonstrate that the brain is more sensitive to those signals than we once thought.” The study is published in the scientific journal Proceedings of the National Academy of Sciences (PNAS).

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