"And then a Plank in Reason, broke,"
“I am dead.”
In terms of possible delusions in living human beings, Le délire des négations — the nihilistic delusion that one is dead — evokes the most harrowing existence imaginable. The French neurologist Jules Cotard first described the syndrome that bears his name (1882, English translation):
I hazard the name of delirium of negations to designate the state of the patients ... in whom the negative disposition is carried to the highest degree. [They are] asked their name – they have no name; their age – they are ageless; where were they born – they were not born; ... if they have a headache, stomach ache, pain in some part of their body – they have no head, no stomach, some even have no body... For some the negation is universal, nothing exists anymore, they themselves are nothing.
Cotard presented the case of Miss X, a 43 year old woman with severe “melancholic anxiety” who tried to end her own life (1880, English translation):
...She affirms that she has neither brain nor nerves, nor chest, nor stomach, nor intestines; all that remains is the skin and bones of the body, disorganized (these are [her] own expressions). This delirium of negation extends even to the metaphysical ideas which were formerly the object of [her] firmest beliefs; She doesn't have a soul, God doesn't exist, neither does the devil. Miss X… being no more than a disorganized body, does not need to eat to live, she cannot die a natural death, she will exist eternally unless she is burned, fire being the only end...
Cotard delusion has been observed in a wide variety of psychiatric and neurological conditions, including psychotic depression, schizophrenia, encephalitis, subdural hemorrhage, arteriovenous malformations, migraine, Parkinson's disease, stroke, and epilepsy (Gerrans, 2022). From a neurobiological perspective, it's nearly impossible to construct a unified theory of the dysfunctional brain systems that underlie the delusion. Hence, some studies have focused on patients who manifest Cotard delusion after stroke, brain injury, or anti-NMDA receptor encephalitis for clues on potential brain regions that may be implicated in these cases.
Two new papers describe the role of depersonalization — an estrangement from one's body or self — in Cotard delusion (Davies & Coltheart, 2022; Gerrans, 2022).
Absence disembodies — so does Death
Hiding individuals from the Earth
Superposition helps, as well as love —
Tenderness decreases as we prove —
One prominent account of Cotard holds that people suffering from the delirium of negation are completely devoid of emotional responses. The nihilistic delusion is an attempt to make sense of this anomalous experience. Davies and Coltheart (2022) are critical of this view because there's no evidence that emotional reactivity is abolished in Cotard delusion. They also cite 12 case reports of patients who show a variety of affective states that collectively encompass anxiety, fear, guilt, distress, paranoia, aggression, agitation, anguish, despair, euphoria, grandiosity, irritability, sadness, and worry.
An alternate account places the anomalous experiences of depersonalization and derealization, rather than lack of emotion, as the central “surprising events” that trigger nihilistic delusions (Billon, 2016; Davies & Coltheart, 2022). These patients describe phenomena such as “I feel myself detached from my own body” and “feelings of unreality and difficulties in deciding whether events ... were real or just imagined”. The injured brain areas in these patients included insular cortex and right temporal-parietal regions.
A Death blow is a Life blow to Some
Who till they died, did not alive become —
Who had they lived, had died but when
They died, Vitality begun.
In contrast, Gerrans (2022) proposes that depersonalization and Cotard delusion result from different ruptures in the sense of self. He provides an extensive and accessible review of the interoceptive active inference model and predictive coding of bodily states in the anterior insula cortex. Depersonalization may arise from imprecise interoceptive predictions, but reality testing remains intact. On the other hand, Cotard delusion represents a complete rupture from reality.
Within this framework, depersonalisation experience involves a selective failure to annex a class of experience to a largely intact hierarchical self-model. The Cotard delusion is a result of the destruction or degradation of that model. It is consistent with this view that there can be overlap between symptoms of depersonalisation disorder and Cotard syndrome, especially while the delusion develops because of nature of self-modelling. However the delusion reports the experience of human life without an intact regulatory self-model whereas in depersonalisation the self-model is largely intact.
A key component of the “depersonalization first, Cotard second” view should account for why the former is relatively common, while the latter is quite rare.
References
posted by The Neurocritic @ 11:31 PM
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