What (if anything) can I do for an internet friend that I'm concerned about?

I have a friend online who has schizophrenia. Originally I was friends with his older brother (we played Xbox live together), and ultimately came to be friends with his younger brother, and even spoke with their mother a few times… so I know the family, at least a bit. However, only the middle brother and I have kept in touch.
I am really concerned about his recent behavior. He has become really difficult to understand, most of what he talks about doesn’t really make any sense. In the last several months he has become increasingly convinced that God is speaking to him, and giving him a very special message for the world, but first he has to decode (?) some kind of numerical puzzle that he is obsessing over.
He’s a really nice guy, the whole family is really wonderful, but I don’t know how to get in contact with anyone else these days. I am not even sure where his brothers live, but I know that my friend lives with his parents. Should I attempt to find his mom and perhaps express my concern, or is that likely to be unwelcome? Aside from having spoken to her a couple of times, she doesn’t really know me. I would hope that the family would recognize that he seems to be delusional, but this has been going on for months and only appears to be getting worse.
I know that in the past he has gone through phases where he refuses to take his medication, and I worry that it is the case now, but I have never seen him this detached from reality before. I’m not sure that it would do any good for me to talk directly to him, but even if I were to try that, I’m not even sure what to say.

Is there anything that I can or should do, or should I just assume/hope that the family is keeping an eye on this?