Diffusion of knowledge

What are the main deciding factors in how pieces of knowledge spreads in the population? Does the factuality of a tenet matter?
I'm thinking of misconceptions such as thinking that schizophrenia refers to multiple personalities. It's a pretty common misconception. It's also a good target for pedantery, so incorrect use will often be corrected.
Now, are either of these sides winning? Will everybody eventually know the proper definition of a schizophreniac, or will the medical community be forced to throw in the towel and find some other word for the condition, leaving 'schizophreniac' as accepted vernacular for persons with multiple personalities disorder?
Does anybody study this shit?

Why would the medical community need a new word? They could give a shit what the "accepted vernacular" is. Doctors and medical texts will still use it correctly either way.