Good question.
I would describe the nature of the racing thoughts, when they come, as false signals from the brain (that I know are ridiculous, but can’t control).
For example, I’m out in public (like in a grocery store) and have an attack, of that kind. My brain could be telling me various annoying things (like everyone is watching me, making fun of me, calling me names, talking about me or thinking I’m crazy). It’s an interesting phenomenon. I compare it to a faulty water faucet, where one just can’t shut the water off, as it‘s leaking all over the place. Normal people can do this - schizophrenics can’t and have no defenses when it happens.
Thankfully, it’s extremely rare for me to have an attack out in public these days. And when I do, it comes on gradually, so I can have time to go home, lie down and rest (the only way to fully alleviate my racing mind).
What I have to still watch out for, for instance, is if I am driving a car and it happens. One does not want to operate a motor vehicle when “hearing voices“ - it is simply unsafe to be out on the road. Generally speaking, I will have plenty of time to get home, before my brain overflows. Thankfully, my racing thoughts (when they do occur) only happen at night, after 4pm. It has something to do with the medication wearing off, as I take that in the morning. Anyway, I generally don’t drive at night anymore, just to be safe.
That is it, in a nutshell. Basically, stress brings this kind of stuff on. If I had to sum up schizophrenia in three words or less, I would say “Sensitivity to stress.”