In the early years, we simply thought of sadness and not a real medical problem. Over the years, researchers have understood a more important aspect of this illness, depression. This should be enough to prove that depression is serious and that there is still so much to discover. By doing more research on depression, we can advance the field of psychology in several ways. First, depression is heavily influenced by brain research. Almost all research into depression will involve the brain or parts of it. Psychology is the study of the brain and what it does, when it does it, in great detail. By learning more about the brain for depression, we will also advance brain research, which will in turn expand the field of psychology. Secondly, depression itself is a medical problem and to know how to treat it, one should consult a psychologist. So, knowing more about what people do when they are depressed can make it easier to diagnose patients because the psychologist knows what to look for. If the research continues, it might give the impression that the patients are fine, but in reality they are showing signs of depression and these signs are the new signs that have recently been discovered with extensive study.