Over the years, I've learned that in one particular study, various kinds of nutritional interventions allowed 90% of institutionalized schizophrenics to live independently on their own. My partner (a therapist) recently started working with a client who is schizophrenic. Turns out the "trigger" for his first schizophrenic episode was fasting (another hint at nutritional aspects). Without going into detail, I've also learned there's a variety of evidence indicating a pathogenic element to it as well, and a lot of evidence indicating gut issues are also a huge factor.
Gut issues, nutritional status, immune system dysfunction, mitochondrial dysfunction, etc., all seem to be important and significant factors in most if not all brain/neurological disorders, including ME/CFS. I've come to believe unaddressed (and significant) structural issues of many different kinds in the spine and skull also play important roles. I rarely think these days in terms of "mental illness". I think more in terms of Central Nervous System dysfunction, and all the many elements that combine to create such difficult health conditions.
Mental illness = methylation problems.
http://metabolichealing.com/michael-s-blog/mental-illness-or-methylation-mutation/
Methylation is required to make neurotransmitters. Therefore, mental illness is actually physical illness.
Also, as we ME patients know firsthand, methylation problems create problems with the mitos. If mito function is associated with mental illness, you can see how it's all interrelated.
There are about 30 diseases associated with methylation problems (both physical and mental), including autism, cancer, Alzheimer's, ME/CFS, anxiety, depression, etc. Treatment for all of these would be more or less the same, i.e. methylation treatment. The same core problem expresses as different diseases in different people due to genetic variations and probably environmental ones too.
However, medically and politically we don't want to be associated with mental illness due to the stigma and poor treatment options currently available.
When the world at large catches on to methylation, the stigma of mental illness will be erased, and there will be a lot less chronic illness.