My Mother in law has developed a new behaviour; an idea or phrase seems to lodge in her brain and she repeats it ad infinitum. My Father in law tries to respond to what she is saying but without any sign that MiL registers what he says. He is clearly distressed by the cycle. Is there a more effective way of managing this situation? Distraction doesn't seem to work and although MiL doesn't respond to what FiL says she becomes more agitated if her behaviour is ignored. Also, is there a recognised term for this behaviour?