A British man has been living with a condition known as Cotard's syndrome for the past nine years that makes him believe he is no longer living, The Telegraph reported.

The disorder, also called the "walking corpse syndrome," is extremely rare, and surfaced after he struggled with severe depression. The man, identified as Graham, convinced himself he was a zombie.

It began after Graham tried to commit suicide by submerging an electrical appliance with himself in his bath; then, when eight months had passed, he told his doctors he felt his brain was missing or dead.

The harrowing scenarios only got worse. He stopped eating, speaking, and smoking because he believed there was no purpose. It became so bad his family had to look after him. At one point, he visited the nearest cemetery to find his grave.

"I didn't want to face people," he told the New Scientist magazine. "There was no point. I didn't feel pleasure in anything. I used to idolize my car, but I didn't go near it. All the things I was interested in went away."

After being told that he should consult neurologists Adam Zeman of University of Exeter in the United Kingdom and Steven Laureys of the University of Liège in Belgium, Graham's brain scan revealed low levels of activity similar to a person in a vegetative state.

"I've been analyzing PET scans for 15 years and I've never seen anyone who was on his feet, who was interacting with people, with such an abnormal scan result," Laureys told New Scientist. "Graham's brain function resembles that of someone during anesthesia or sleep. Seeing this pattern in someone who is awake is quite unique to my knowledge."

The doctors believed his anti-depressents could have induced a low metabolism that produced those results in brain scans, but more research was needed.

"He was a really unusual patient," Zeman said. "His experiences no longer moved him. He felt he was in a limbo state caught between life and death."

The man eventually overcame his condition and is beginning to live a normal life after months of extensive therapy and treatment. While Graham says he's not 100 percent on track, he doesn't feel brain-dead anymore and he can step out of his home and "feel a lot better" than before.

"I'm not afraid of death. But that's not to do with what happened - we're all going to die sometime. I'm just lucky to be alive now," he said.

Cotard's syndrome was first discovered by Jules Cotard in 1882. Patients with the condition may believe they lost organs, blood, parts of their body, or even their soul. Experts are unsure how common the disorder is today.