Researchers discover connection between immune response and depression

By Staff Writer

An individual who is feeling blue during a time of sickness may not just be down because of their physical condition. A team of researchers from Vanderbilt University has found that some of the immune system cells that respond to infection may also contribute to depression, increasing an individual’s risk of needing help from rehab facilities.

Cytokines play an important role in the immune system’s response to foreign bodies. However, they may also cause potentially harmful changes in brain chemistry. The researchers found that they increase the activity of serotonin transport, which are proteins that regulate levels of the neurotransmitter in the brain. When these proteins become more active, serotonin levels drop.

Serotonin is directly related to mood. Low levels of the neurotransmitter have been associated with an increased risk of depression and anxiety disorders.

To confirm the link between increased cytokine activity and depression, researchers induced greater immune activity in mice. They found that the mice exhibited behaviors that correlated to human depression. Researchers then measured brain levels of serotonin and found them to be very low.

They believe that their findings may lead to improved diagnostic and treatment tools for depression.