Rock and a hard place. On one hand, if we say it's never "permanent," that goes against all of the evidence showing that some people have it in varying degrees all through life. If we say it's "temporary," but it comes back, then that theory is blown.
I've been diagnosed with depression because I meet most of the criteria. But, sometimes I wonder if it's some other type of emotional problem. I think I have some PTSD because of several traumatic experiences, but my doctors don't seem to want to go there. Regardless of the label, it's anxiety, fatigue, hopelessness, isolation, and more. Why I've been stuck in a rut for several years in a row is beyond me. It feels permanent, but my docs all say that it could turn around at any time. I hope they are right.
But, I also believe that if I do manage to get out of this bad place, I will need to be prepared to fall back in later, too. It's a vicious cycle.