Physicians have long observed a mystifying phenomenon: After a bout of infection or an autoimmune disease flare-up, some people experience prolonged mood swings, emotional dysregulation, and changes in behavior. But the precise connection between inflammation, mood, and behavior has remained elusive.
- By MARK GAIGE
Now, two new studies from Harvard Medical School and Massachusetts Institute of Technology, published April 7 in Cell, detail the steps of an intricate brain-immune crosstalk that accounts for this long-known but poorly understood observation.
The work, conducted in mice and funded in part by the National Institutes of Health, pinpoints the molecular roots of the phenomenon and shows how immune molecules called cytokines influence brain activity.
Scientists already knew that cytokines affect emotions and brain function, but how and where in the brain this occurs has thus far remained unclear. The new research maps a network of cytokine signals that interact with specific brain cells to regulate mood, anxiety, and social behavior.
If confirmed in further studies in animals and people, these findings could lead to new therapies for autism and anxiety disorders. These treatments would work indirectly by altering immune chemicals to calm the immune system rather than by acting directly on the brain like traditional psychiatric drugs do. Those drugs must cross the protective blood-brain barrier to change brain chemistry directly, while the new approaches could work by adjusting immune signals from outside the brain.
