One of the more fascinating psychotic conditions in the medical literature is known as Cotard’s syndrome, a rare disorder, usually recoverable, in which the primary symptom is a “delusion of negation.” According to researchers David Cohen and Angèle Consoli of the Université Pierre et Marie Curie, many patients with Cotard’s syndrome are absolutely convinced, without even the slimmest of doubts, that they are already dead.

Some recent evidence suggests that Cotard’s may occur as a neuropsychiatric side effect in patients taking the drugs aciclovir or valaciclovir for herpes and who also have kidney failure. But its origins go back much further than these modern drugs. First described by the French neurologist Jules Cotard in the 1880s, it is usually accompanied by some other debilitating problem, such as major depression, schizophrenia, epilepsy or general paralysis—not to mention disturbing visages in the mirror. Consider the case of one young woman described by Cohen and Consoli: “The delusion consisted of the patient’s absolute conviction she was already dead and waiting to be buried, that she had no teeth or hair, and that her uterus was malformed.” Poor thing—that image couldn’t have been very good for her self-esteem.