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Worry about your health at times? Well, at least you don't believe you have no body parts, blood, or organs, or consider yourself dead or immortal. Yet those are among the beliefs plaguing people with Cotard’s syndrome, an illness discovered in 1880 that's extremely rare and awful when it strikes, Medical Daily reports.

In case you doubt it, there are two studies (here and here) that found a .57% and .62% rate of Cotard's, respectively, in large groups of psychiatric patients.

Researchers say the condition—also known as "walking corpse syndrome"—often begins with severe depression and a health anxiety that can inspire odd complaints. One 28-year-old woman, for instance, told hospital staff that her stomach was missing and her liver was "putrefying." The report on her case notes that the syndrome generally affects those in middle-age or later years, but when young people are diagnosed, they are overwhelmingly (90%) female.

Over time, patients may believe they don't exist or lack body parts, which can trigger a slew of problems including poor hygiene, self-harm, and a refusal to eat.

"There was no point in eating because I was dead," a sufferer identified as Graham told New Scientist in 2013. He was the first Cotard's patient to get a brain scan, and a neurologist likened the brain function the scan showed to "that of someone during anesthesia or sleep." Experts say antidepressants and antipsychotics can help, along with shock therapy, which may explain the low rate of Cotard's today.

Drugs and psychotherapy worked so well for Graham that he was able to live on his own. "I don't feel that brain-dead anymore," he says. "Things just feel a bit bizarre sometimes." (See which US states have the most mental illness.)

This article originally appeared on Newser: Rare Disease Can Make You Think You're Dead

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