FWIW, when a psychiatrist we know was asked if he thought some people who are being treated for mental illness were actually demonically possessed he said, ”Yes and I can tell the difference.”
It seems to me that we Christians ought to be able to follow the examples of Christ and the early church and deal with these sorts of things in the name and by the authority of Christ. There’s just so much teaching that has been neglected over the many centuries since the early church. - I can remember many years ago, I had a great uncle who was in a mental hospital; he was always muttering to someone or something else when I was there. I took authority over it in the name of Jesus Christ, and that stopped and never happened again. - I don’t know what your religion is, but that’s the truth about my experience in that regard. - We just don’t have the teaching in these days, but I was simply following scripture the best I could.