Demon possession is a real thing ( e.g. Mark 5:1-20). Recently, a board certified psychiatrist  named RIchard Gallagher from New York wrote an article on current manifestations of this evil. The article is titled As a psychiatrist, I diagnose mental illness. Also, I help spot demonic possession. It describes how he differentiates between demonic possession and mental illness. It also talks a little bit about the different factions within the medical community, some who are sympathetic toward his thinking and some who are skeptical and even openly derisive . I found another article that describes the case of a woman he called “Julia” to hide her identity. I do not know what else to say about these articles other than that they were a very interesting read. I have never seen anything like this up close, but have heard first person accounts of such things in Mexico from people I trust, take these topics seriously and are not given to exaggeration.