 Decline in cognitive function after surgery occurs most commonly in older patients and patients undergoing major surgeries, such as heart surgery. Postoperative Cognitive Dysfunction POCD may last a prolonged period of time while Postoperative Delirium POD is a more acute disturbance in attention, awareness and cognition. The cause of POCD and POD are not fully understood, however some of the pathophysiology of POCD is similar to that of Alzheimers disease AD. 