The Clinical Center has requested that the BEIP install two additional Patient Electronic Monitoring Systems (PEMS) on the 5E and 3E Nursing Units. This system, which alerts the nursing staff when a patient (or more than one) is leaving the nursing unit, is a welcome aid in the care of patients with Alzheimer's disease or other dementias. The system is based on a wristwatch-size radio transmitter worn by the patient. Detector units, placed at each of two exit doors, sense the presence of any patient wearing a transmitter watch. With the detection of a patient's transmitter, a microprocessor-based controller locks the exit door, activates an alarm, and sends the patient's name and location to a personal computer, which displays and records the time and date of each attempt a patient makes to leave the unit.