Why is depression a illness?

Answer 1

Doctors call depression a disorder because dis means not, and order means everything should be in it's place, so dis order, not in place, means that your body/brain has something wrong with it and so the doctors call it that.

Answer 2

Clinical depression would be better categorized as a disorder rather than a disease. The distinction is somewhat subtle. With a disease, something has happened to you, either you have been infected with a pathogenic organism, or you have suffered malnutrition, or physical injury resulting in a disease. With aging you get degenerative diseases because the body is wearing out. Conditions don't have those kinds of origins. Something just isn't working correctly. In the case of clinical depression, the brain is in an abnormal state. It's hard to say how this came about. But it's a problem.

Answer 3

Depression is classified as an illness because there are distinct anatomic and physiologic changes that occur, a set of defined symptoms and several accepted treatments that can reduce or eliminate symptoms.