This may not be depression in her case, but there is a good chance it could be and a good psychiatrist should be able to determine this.
As for the treatment
of clinical depressive and anxiety
dissorder..... there is no cure, BUT it can be treated and managed. In most cases this condition is a lifelong affliction, but with proper treatment it can be put back in a remissive state. That doesn't mean that it is gone forever though.
Oh, you mentioned how smart and intelligent your daughter is.