Depression is a serious medical illness; it’s not something that you have made up in your head. It’s more than just feeling "down in the dumps" or "blue" for a few days. It’s feeling "down" and "low" and "hopeless" for weeks at a time. more>>
Occurrence with other serious illnesses: Depression may coexist with other serious illnesses, such as heart disease, stroke, HIV/AIDS, diabetes, and Parkinson's disease.