Recent studies have caused a growing number of scientists to conclude that depression is just as much of a physical illness as it is a mental illness.  According to The Guardian, the basis of the study is as such: everyone feels miserable when they are ill. Many sluggish behaviors associated with depression can be categorized as sickness behavior.

TIME reports that one explanation tying both the physical and mental ailments of depression together is inflammation of the brain. This occurs when the immune system is called into action after the body suffers a wound.

A set of proteins called cytokines is integral to setting off this brain inflammation, which is why people tend to feel down when they are ill. The Guardian reports that both brain inflammation and cytokines tend to rocket during depressive episodes. Furthermore, completely healthy people can also be temporarily put into a depressed, anxious state when given a vaccine that causes a spike in inflammation.

Because infections are known to cause inflammation, some scientists have gone so far as to label depression as an infectious - but not contagious - disease. However, not all scientists are willing to do the same, as obesity and a diet full of trans fats and sugars have also been known to cause inflammation.

As a result, it has been hypothesized that depression is likely the result of the brain tricking itself into sickness mode.  This theory of linking depression with a physical condition is comforting to many. According to Vice, Kings College psychiatrist Carmine Pariante says that we are between five and ten years away from a blood test that can measure the level of brain inflammation in depressed people.

If this blood test idea is realized, we could maybe even be five to ten years away from a potential "cure" for depression.