I work in a nursing home on an alzheimers/dementia floor and I know exactly what you mean. There is no way to change these people or the opinions they have about certain races. I am one of the only white staff members and there are certain residents who will only respond to me and allow me to care for them. Alternatively, there are residents who absolutely refuse to let me care for them. We just adjust our assignments accordingly, avoid confrontation and any other problems.