People with Cotard's Delusion believe they're on the wrong side of The Walking Dead TV series, meaning they think they're actually dead. How is it possible to treat them? Can you "prove" to a patient that they're still alive?
The New Scientist's Mindscapes column has a brief but fascinating profile of man identified only as "Graham" who suffers from a rare delusion known as Cotard's syndrome. Despite walking and talking and eating every day, Graham is convinced that he's dead.