"So if people with depression show classic sickness behaviour and sick people feel a lot like people with depression – might there be a common cause that accounts for both? The answer to that seems to be yes, and the best candidate so far is inflammation – a part of the immune system that acts as a burglar alarm to close wounds and call other parts of the immune system into action. A family of proteins called cytokines sets off inflammation in the body, and switches the brain into sickness mode...it starts to look as if depression is a kind of allergy to modern life''

Caroline Williams