Can any estate planning be created if the subject has dementia?

My uncle was diagnosed with dementia several years ago and is now in declining health. He is the owner of the house he lives with my aunt and his is the only name on the deed. He has steadily refused to engage in any type of estate planning and is currently becoming more paranoid and irrational. My aunt is the sole caretaker and has been the only person earning income to support her family for nearly ten years. Under these cirstances, is there any recourse under US law in which my aunt can ask that some type of power of attorney, will or other form of estate planning be created so that she can avoid having her husband p away interstate?