Gotcha. Yes, the derealization and the depersonalization are very concerning. I'm still reading what I can about recent research on VSS and its psychiatric correlations. It appears no one knows whether this is simply a reaction to the visual disturbances (which in BK's case include what the rest of us would call "visual hallucinations") but they're weird ones, as they are apparently always "afterimages" - the sudden reappearance of something one has already seen.
This can accompany various forms of dementia but it can also be a side effect of some medications. In VSS, it is part of the illness and is documented. These bizarre and startling reappearances of scenes or objects or people from the past are disturbing to patients (not all VSS sufferers have this, but a high proportion of them do - and BK describes it very well).
I think this is a boat load of symptoms for a person in their teens to deal with (he says the symptoms started abruptly at age 9 - and abrupt start of symptoms is common in VSS). My own trigeminal neuralgia just popped up one morning, waking me from sleep and heading me out to the ER as fast as I could rouse my husband. I say this because neurological disorders typically have a different kind of onset than psychiatric ones.
Could he have both schizophrenia AND VSS? Yes. But what a poor draw in the health lottery that would be. Schizophrenia is often genetic and runs in families, no such association for VSS that I can find so far. And, I will say, what writings we do have from him do not fit my own model of l"schizophrenic writing," a topic which I am very interested in. I now wish i'd kept every scrap of it that I encountered but we didn't have cell phones back in those days.
Here's an article about the common accompanying conditions and symptoms of VSS (schizophrenia is not one of them):
In this paper we review the visual snow (VS) characteristics of a case cohort of 32 patients. History of symptoms and associated co-morbidities, ophth…
www.sciencedirect.com
So, if BK is indeed schizophrenic AND a VSS sufferer, he's a rare bird indeed.
(I just found one article on the relationship between schizophrenia and VSS - but it's not about actual clinical data, it's about the parts of the brain involved). Anyway, I'm off to read that too - as it is a very intriguing question. I have a bit of case study info that some might find interesting (about a particular VSS sufferer and their mental health),