There are about a hundred accounts in the medical literature of people displaying what is now known as Cotard's delusion. It is also sometimes known, unsettlingly, as walking corpse syndrome. If you were to develop Cotard's delusion you might look in the mirror and find your reflection suspicious, or you might cease to feel that the heartbeat in your chest was yours, or you might think parts of your body were rotting away. In the most extreme cases, you might think you'd become a ghost and decide you no longer needed food. One of Cotard's patients died of starvation.
— You are now less dumb
by David McRaney