Why Do We Feel Awful When We’re Sick?
Jennifer Zhao ’18

A new study in Science has uncovered a molecular mechanism that explains why sick people experience foggy heads and fatigue, which scientists have collectively described as “sickness behavior.” While our body diverts energy to fight pathogens, our immune cells also produce a molecule called interferon-β, which stimulates receptor molecules in the brain to produce a blood-brain barrier, a protective system that excludes most pathogens and immune molecules from the brain. A study with mice that were exposed to a brief illness were found to carry this receptor and were more vulnerable to depression and impaired cognitive abilities, essentially altering the brain’s behavior during an infection. Researchers hope they can use this new molecular information to find ways to stop the unwanted side effect of sickness behavior in cancer patients who receive interferon treatment.