Is depression a form of 'sickness behavior'?

A new study has demonstrated that depression is a result of inflammation caused by the body's immune system.

George Slavich, a clinical psychologist at the University of California in Los Angeles, said that depression does involve psychology, but it also involves equal parts of biology and physical health, the Guardian reported.

According to the study, a family of proteins called cytokines sets off inflammation in the body, and switches the brain into sickness mode.

Both cytokines and inflammation have been shown to rocket during depressive episodes and in people with bipolar to drop off in periods of remission. Healthy people can also be temporarily put into a depressed, anxious state when given a vaccine that causes a spike in inflammation.

Turhan Canli of Stony Brook University in New York thinks infections are the most likely culprit, and even goes as far as to say that we should rebrand depression as an infectious but not contagious disease.