If someone has mdd (major depression disorder), could he/she die?!

If someone has mdd (major depression disorder), could he/she die?

without the commiting suicide stuff

I assume you mean are they more likely to die than general population if suicide is accounted for. The answer is yes. They are more likely to suffer all kinds of diseases and disorders at a greater rate than the general population and may not be as able to take care of themselves. Some of these include heart disease (linked to serotonin dysfunction), neurological disorders from fibro-myalgia to MS, arthritis, auto-immune disorders, smoking related cancer and diseases (from smoking), alcoholism, substance abuse disorders, and obesity and related health complications. All these health problems put together contribute to a shorter life expectancy. Sad, but health often improves when the depression is treated.

I'll give one example. People with heart disease very often also suffer from depression. Those who suffer from both are twice as likely to die within five years as those who only have heart disease. When both are treated, those with both survive at nearly the rate those with only heart disease survive. Depression is very treatable and doesn't have to shorten your life.