A growing number of scientists are coming to the conclusion that depression is at least as much a physical condition as it has to do with the mind.
One explanation is inflammation, which is caused by a part of the immune system that gets called into action when the body suffers a wound, the Guardian reports.
A set of proteins called cytokines sets off this inflammation in the body. This process is why people tend to feel down when they fall ill.
And so scientists think the brain may be tricked into feeling depressed through a process akin to an allergic reaction.
Read more at the Guardian