You rang? 
Well, what you've got there is part of schizophrenia. Schiz is
actually a vague cluster of disorders that involve:
- distortions of reality
- disturbances in thought and language (this covers
hallucinations)
- poor social skills
Sounds like the trolls on SGForums, doesn't it?
I wouldn't be particularly concerned about schizophrenia if I were
your friend -IIRC, the last time I checked up on the figures, there
less than a 5% chance of a schizophrenic person's child developing
schizophrenia. However, I'd stay well away from drugs if I were
your friend - there's plenty of evidence that drug use triggers
schizophrenia in people who are predisposed to it.
More likely than not, your friend's mother is on antipsychotics
like Resperidone, which are meant to keep her from going overboard
and becoming a danger to herself or others around her. The
prognosis is fairly poor - if you've kept a schizophrenic
individual safe, clean, well-clothed and well-fed, chalk it up as a
roaring success.
In your friend's mother's case, it appears to be pretty much the
textbook definition of paranoid schizophrenia. She doesn't see or
hear any imaginary people. Instead, she infers that they are there
and out to get her by objects and events that she takes as evidence
of their existence - though distortions of reality, anything can
look suspicious.
I'm probably being hard-headed about it, but I haven't seen any
research that convinces me that a person can have multiple
personalities, instead of simply acting in an uncharacteristic
manner as a reaction to severe stress.
