I can't help noting an article published by The Guardian and linked at unknowncountry.com questioning, in general, whether "mental illness" is a valid clinical diagnosis. The gist of the unknowncountry commentary is that, no, there isn't really such a thing. People aren't mentally ill; they're just creatively different.
As I've opined extensively in the past, this is the 800-pound gorilla in the paranormal room: people who fit the clinical diagnosis of mental illness tend to appear on sites and talk radio shows devoted to the paranormal (and the right-wing).
My personal experience is that there IS such a thing as the classic diagnosis of mental illness, and that those who are mentally ill truly are unable to function in our consensus reality. At all. They can't communicate; they can't work; they can't perform even the most elemental tasks of self-sufficiency.
If anything, the United States lives in profound denial of the problem of mental illness. And we see the consequences daily: in our leagues of homeless, in our mass homicides, in our exploding prison population.
On a less consequential level, mental illness-denial contaminates any discussion of metaphysical topics and prevents any serious, rational investigation into what (I believe) to be valid, extraordinary experiences. Scientists won't touch it, and I don't blame them.
The mentally ill are people who truly warrant our help, support, and treatment. Not, necessarily, our belief.