I guess I believe that things rarely get better than we expect them too.They may not get as good as we'd like, but they rarely exceed our expectations. "Argue for your limitations, and they're yours."
I don't think it makes any sense to expect things to "go back to the exactly the way they were". This might vary with individuals. Personally, I have no recollection of a "time before", and I'm sure that's different from have an concept of "before and after". Regardless, life is like a river and it moves on. No matter what changes we experience, they are CHANGES, so today is always different from yesterday.
As far as the neuroscience goes, I've read about things like OCD, where brain studies have shown altered pathways that are associated with the condition and, after therapeutic intervention that appeared to result in decreased symptoms, those pathways had altered to become more "normal". I think if you can change a normal brain in one direction it stands to reason you can change it back. I'm sure every case is different, but I wouldn't want to put an arbitrary limit on what's possible.