Wow, that is surprising. I would have expected psychotherapy to be quite helpful to some of them much the same way medication is somewhat helpful to some people or religion is helpful to some people.
I would not expect all of them to have the same combinations of problems, but just being in prison should leave some effects that I'd expect would be helped by psychotherapy to some extent.
Yes, the work by Walsh, Pfeiffer and others is encouraging. For example, one of them says that 4% of people with schizophrenia improve dramatically by eliminating gluten. While this is not a cure for scizophrenia, for those 4% it is life changing. http://alternativementalhealth.com/articles/default.htm#w
What are the chances that an HMO doctor is going to be able to really consider the many possible contributing factors for a mysterious illness when the patient's insurance company is only paying for 15 minutes of time?