Cotard delusion

The Cotard delusion (also Cotard's syndrome and walking corpse syndrome) is a rare mental illness in which an afflicted person holds the delusion that they are dead, either figuratively or literally; yet said delusion of negation is not a symptom essential to the syndrome proper. Statistical analysis of a hundred-patient cohort indicates that the denial of self-existence is a symptom present in 69% of the cases of Cotard's syndrome; yet, paradoxically, 55% of the patients present delusions of immortality.