US Patent 7764167 Monitoring movement of an entity in an environment

Whether a person suffering dementia has left their flat unaccompanied can be determined by identifying an event indicating opening of the front door of the flat, determining whether the flat was occupied by more than one person prior to the door opening, determining whether there is inactivity in the flat following the door opening and sending a notification to a communications terminal of a caretaker if the flat was occupied by only one person and if there is inactivity in the flat.