Study: Poor Immune System May Lead to Anti-Social Behavior

The immune system directly affects and even controls social behavior, scientists said.

Researchers at the University of Virginia School of Medicine discovered that the immune system affects the desire to interact with others, and that problems in the immune system could contribute to the inability to interact.

"The brain and the adaptive immune system were thought to be isolated from each other, and any immune activity in the brain was perceived as sign of a pathology," Dr. Jonathan Kipnis, chairman of the University of Virginia's Department of Neuroscience and author of the study, said in a news release.

"And now, not only are we showing that they are closely interacting, but some of our behavior traits might have evolved because of our immune response to pathogens," he added.

In the study, the researchers discovered that meningeal vessels directly link the brain with the lymphatic system. The findings were contrary to years of old textbook knowledge that the brain has no direct connection to the immune system.

The researchers also found that the relationship between people and pathogens could have directly affected the development of social behavior. The connection is what allows people to engage in the social interactions necessary for the survival of the species while developing ways for the immune systems to protect people from diseases that are carried through these interactions.

The researchers pointed to a specific immune molecule, interferon gamma, which seems to be critical to social behaviors in a variety of species, including mice and flies.

The molecule is normally produced by the immune system in response to bacteria, viruses or parasites. But the researchers found that blocking the molecule in mice made regions of the brain hyperactive, causing the mice to become less social. However, upon restoring the molecule, the mice's behavior became normal again.

The researchers noted that a malfunctioning immune system may cause "social deficits in numerous neurological and psychiatric disorders." According to the researchers, the discovery could lead to further studies in battling neurological disorders and understanding human behavior.

"Our findings contribute to a deeper understanding of social dysfunction in neurological disorders, such as autism and schizophrenia, and may open new avenues for therapeutic approaches," Vladimir Litvak of the Department of Pharmacology who worked on the study, said in a statement.

The findings of the study were published online in the journal Nature.