By and large, mental illness can be healed. The best methods are holistic. Therapy can be part of that, with a very good therapist. Healthy eating and exercise and sunlight can have much more of a healing effect than you could imagine, as well. Also, becoming more creative, journaling, dancing, doing an art form, and being more social are all good.
If we do what we can do each and every day, we can heal almost anything. It doesn't depend on the illness so much as it depends on us. And I've seen this many times, with mental illness, with brain disorders and brain injury, and with physical illness, as well