My Father was diagnosed with Dementia, and has progressively become worse. He now thinks everyone is against him. Who do we turn to?

Look in the paper and call hospitals there are a lot of neuro support groups out take him to a doc in that field and have a good work-up done and do research and get in a support group talking to others in the same situation is priceless and go on from there he may have to be placed at some point.