Cotard's Syndrome or Walking Corpse Syndrome as it's colloquially known, is a belief held by a person that she is actually dead, decomposing or simply doesn't exist. It has been linked to depression as well as to those who are chronically deprived of sleep or suffer drug psychosis, but is still largely misunderstood by science. The disorder has also been connected to Capgras Syndrome, a condition where a person thinks someone in her life has been replaced by an imposter or a duplicate. There is a division in the brain between the visual face recognition area and the part that associates emotional responses with that recognition, according to Psychology Today. Thus, a person suffering from either disorder may not even recognize herself and genuinely convinces herself that she doesn't exist.