Would people with metabolic syndrome ("pre type 2") also have this risk, or would fully evidenced type 2 be necessary?

An awful lot of people live semi continuously for years in a pre diabetic state. Not "I am not diabetic" and not "I have diabetes" -continually reminded by their medical advisors to cut down on their intake and drinking, exercise more and fix their sleep hygiene. "Or you'll have to go onto the drugs"

My thought is yes. There has to be neuronal death as the neuron becomes less sensitive to insulin and metabolize glucose.

Pre-diabetes undoubtedly leads to impaired glucose metabolism in neuronal cells.