near death experience
Some patients with Cotard's syndrome think they are dead. iStock

Cotard's syndrome leads patients to deny their own existence or the existence of some of their organs. One of the largest studies to date on the topic has now confirmed that brain injuries may be playing a significant role in the development of the condition, which is more often described as a psychiatric disease.

Also known as the 'Walking Corpse Syndrome', it is very rare and has been documented only in a handful of subjects who were manifesting a range of nihilistic delusions. Cotard's syndrome was first described in 1880, but since then, very little progress has been made to understand its causes and how it could be treated.

As such, it does not form part of the DSM-5 classification, the international reference to help psychiatrists make accurate diagnoses of mental health disorders.

"Though I cannot specifically comment on why Cotard's was left out, I presume it has something to do with the paucity of research completed on the topic," Aradhana Sahoo, from the Mayo Clinic (Minnesota) told IBTimes UK.

"While a number of case reports detailing individual presentations of Cotard's syndrome in patients have arisen over the years, few scientific studies have been published on the disorder."

In new research now published in Clinical and Research Reports, Sahoo and colleagues searched through the Mayo Clinic's database to identify patients that had been seen over the past two decades at the institution as they were suffering from Cotard's syndrome.

They were able identify 18 patients seen at the clinic between 1996 and 2016 whose file was associated with the following search terms in the database - Cotard's syndrome, delusion of negation, nihilistic delusion, walking corpse syndrome, delusion of missing organs, denial of existence, and idea of damnation.

After more careful analysis, the researchers found that 12 of them fitted the Cotard's syndrome diagnosis, which for such a rare disease makes for quite a robust sample.

"I was surprised myself when the search came up with this many patients. I don't believe there is much data out there on the prevalence of Cotard's syndrome. However, this study looked at patients at our institution over 20 years and came up with this number, which is quite impressive," Sahoo said.

Killed by the staff

Of the 12 patients identified as having evidence of Cotard delusions, eight were male and four were female with a median age of 52 years. Previously, most of the case reports published on Cotard's syndrome had involved older women. Although it is hard to tell if there is a gender predilection in this syndrome due to the small size of the sample, it's interesting to note a different pattern compared to what had been seen before.

Eight patients believed they were dead, three of them saying they had been killed by the medical staff. For instance, one of them thought that he had died during an operation while another thought he had been stabbed while staying in his retirement home.

The four other patients reported that they were dying, with three of them indicating that their organs were being destroyed by worms, bugs or viruses.

Psychiatric history

The scientists investigated Cotard's connection to other psychiatric neurological conditions, as they think this is essential to identify appropriate treatment modalities.

They first looked at whether patients had a history of psychiatric disorders, finding that this was the case for eight patients. Diagnoses of schizophrenia, depression, and substance abuse were reported and one of them even had Capgras syndrome - the irrational belief that a familiar person has been replaced by an impostor.

Five individuals presented with neurological symptoms at the time of their Cotard diagnosis such as seizures and headaches. Examining the available brain scans, scientists showed that seven patients had suffered from brain lesions.

Although more research will be needed to make sense of all this data and find the causes of the syndrome, this study is a first useful step to characterise the condition better - and potentially to find new therapeutic alternatives.

"Cotard's syndrome has long been hailed as a psychiatric illness, but growing literature on the topic suggests that it might cross over to the realm of neurology, as well. We saw several patients who suffered insults to the brain and ended up presenting with Cotard's even though they had no personal history of psychiatric illness or any risk factors. Overall, we hoped to delve into the pathophysiology of Cotard's syndrome and to try to understand why it occurs so we can better treat patients who have it," Sahoo explained.

Over the coming years, a range of research questions will have to be addressed. This includes studying which drugs are more effective in treatment and whether or not injury to the brain is really involved in the development of the disease.

"The main problem standing in the way of scientific studies on this illness at the moment is the scarcity of presenting patients as it is a rare condition," the researcher concluded. "But the mantra in medicine is that a syndrome is rare up until you or a loved one has it. It is important as researchers and clinicians that we continue to educate ourselves so that we are able to adequately give our patients the care they need."