I had an aunt who had schizophrenia (and died at the early age of 40), so I'm always interested in anything having to do with this disorder and other "mental" disorders. 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 and various gut issues as well.
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 structural issues of many different kinds in the spine and skull can also play important roles. I rarely think these days in terms of "mental illness". I think more in terms of Central Nervous System dysfunction, Autonomic Nervous System dysfunction, and all the many elements that effect them, which combine to create such difficult health conditions.
BTW, I have a positive diagnosis for Lyme, including Bartonella, Ehrlichia, and Babesia. I feel fairly certain a big part of my cognitive issues are a result of this "brain disease", and anticipate that if I can somehow overcome these infections, I can overcome my cognitive difficulties as well.