Australasian Science: Australia's authority on science since 1938

The Walking Dead

By Tim Hannan

People with the Cotard delusion are convinced that they are dead.

From the recent popularity of zombies in literature, television and movies, it would seem that many people are fascinated by the notion of the “undead”. As entertaining as the notion of “dead but not dead” bodies may be, believing that you are actually dead can be rather unsettling for sufferers of one delusional disorder.

The belief that one is dead or non-existent is known as the Cotard delusion, after the French neurologist who reported a woman manifesting this idea in 1880. Characterised by nihilistic delusions concerning one’s own body, the Cotard delusion may be accompanied by acting as if dead, displaying muscular rigidity, mutism and/or a refusal to eat.

Jules Cotard described a woman who believed that she lacked a brain, stomach and intestines. Perceiving no need to eat, she died of starvation. A century earlier the Genevan naturalist Charles Bonnet described a woman who, after a blow to the neck, suffered partial paralysis and a temporary loss of speech. After recovering her language she insisted that she was dead, and demanded that her servants dress her in a shroud and lay her out as a corpse.

The medical literature reports that many with the delusion exhibit a psychotic depression, with features of anxiety, delusions of guilt and auditory hallucinations. However, others display the nihilistic beliefs in the absence of mood or psychotic symptoms, with these people usually developing the delusion as a result of organic brain damage, such as dementia, traumatic brain injury, cerebral infection, stroke or other cerebrovascular disorders. One report described a case in which the delusion emerged after a period of voluntary starvation.

There is some evidence that premorbid personality characteristics influence the development and nature of delusional disorders. One theorist has argued that the Cotard delusion is more likely to occur in people with an internal attributional style – that is, a preference to ascribe the cause of a pleasing or undesired event to one’s own behaviour, thoughts and feelings. In contrast, those with an external attributional style – who attribute events to the actions of others – are thought to be more likely to develop disorders that co-occur with paranoia – such as Capgras syndrome, in which the sufferer believes that family members have been replaced by imposters (AS, May 2013, p.35).

Current theories hold that the bizarre features of the Cotard delusion result from the presence of two different brain impairments at the same time.

First, the patient has an abnormal somatic experience that provides the basis for the content of the false belief: she experiences her own body as strange, unreal or disconnected from reality. Attributing this feeling of depersonalisation to internal causes, the patient forms the idea that the novel sensations result from a cessation of normal bodily functions.

Second, the sufferer is unable to reject this strange idea on the grounds of its implausibility due to dysfunction in a “belief evaluation system”. This dysfunction causes the patient to entertain the delusion that she is dead as the best explanation of the strange somatic experience.

While neuroimaging has produced variable results, the brain regions generally identified as dysfunctional include those associated with face recognition, including the fusiform gyrus, and the emotional processing of stimuli, which is centred on the amygdala. It is hypothesised that, as in the Capgras delusion, the patient discovers that she experiences no emotional reaction when she looks at other familiar faces, and concludes that she is experiencing a significant physical problem.

Some patients recover without intervention – usually those with evidence of an organic pathology. Others respond well to pharmacological treatment, especially antidepressants and antipsychotics, although some display a relapsing and remitting course. Bonnet’s patient was reported to largely recover after being given opium as a sedative, although it was noted that she would periodically entertain this belief thereafter.

Interestingly, while those with the Cotard delusion adamantly affirm that they are dead, a high proportion also state that they are also immortal. For these sufferers, the idea of being both dead and immortal does not appear to be more strange or illogical than that of being “dead but not dead”.

A/Prof Tim Hannan is Head of the School of Psychology at Charles Sturt University, and the Past President of the Australian Psychological Society.