A smart and scalable dementia assistant device is provided that converses with a patient in voices familiar with the patient. It utilizes content learned from the patient and content provided by family, friends, caregivers, and doctors, and autonomously adjusts conversations based on the changing state of the patient's dementia state. The device autonomously controls IoT devices (e.g. doors, elevators, tvs, medical dispensers) to help and assist the dementia patient using oral and IoT sensors.