The<unk>  or<unk> 's syndrome, also known as nihilistic or negation delusion, is a rare neuropsychiatric disorder in which a person holds a delusional belief that he or she is dead, does not exist, is putrefying or has lost his/her blood or internal organs.  Rarely, it can include delusions of immortality.
It is named after Jules<unk>  (1840–1889), a French neurologist who first described the condition, which he called le délire de négation ("negation delirium"), in a lecture in Paris in 1880.
In this lecture,<unk>  described a patient with the moniker of Mademoiselle X, who denied the existence of God, the Devil, several parts of her body and denied she needed to eat. Later she believed she was eternally damned and could no longer die a natural death.
Young and Leafhead (1996, p155) describe a modern-day case of<unk>  in a patient who suffered brain injury after a motorcycle accident:
It can arise in the context of neurological illness or mental illness and is particularly associated with depression and derealization.
Treatment is difficult, and tricyclic and serotoninergic antidepressant drugs have shown little efficacy.  Electroconvulsive therapy has shown greater promise, "curing"<unk> 's sufferers in five studies of its efficacy with that treatment.
Cotard delusion
Fregoli delusion
Capgras delusion
Monothematic delusion
Homicidal ideation
Suicidal ideation
Suicide ideation
Schizotypy