How long do young adults have major depressive episodes for?

Varies: Some adults have a single episode of major depression that lasts 2 weeks to several months, and never have one again. In others, the first episode of major depression is a prelude to a lifelong struggle with recurrent depression. In general, the stronger your family history of depression is and the more episodes of depression you've had, the more likely it is that you will have future episodes.

Varies,at least 2wks: To qualify for the diagnosis of major depression, the symptoms of concern must last at least 2wks, they can last as long as to become chronic.

Depends on treatment: With appropriate treatment, depressive episodes can be cut short. Cognitive Behavior Therapy and antidepressant medications are effective in successfully treating depression. Generally, the sooner one is treated the shorter the episode.