In their study of uncommon psychiatric syndromes Enoch & Trethowan (1991) provided a haunting clinical vignette. They described a patient who said that her body was decomposing and disappearing and that eventually she would be “just a voice”. Another patient suffering from the same condition described himself as a “dead star” orbiting an inert galaxy. The Cotard delusion, from which these patients suffer, was described by Jules Cotard in 1882 as a “délire de négation”, a delusion of inexistence (Cotard 1880, 1882, 1884, 1891; Debruyne et al. 2009). It is also described as a paradoxical belief that one is dead. The current cultural fascination with zombies provides the metaphor of “walking corpse” syndrome to describe the condition. However, as with many psychiatric disorders, perhaps the most telling descriptions and explanations of the phenomenon were provided in the nineteenth century, in this case by Cotard himself. He described his patient thus:
Miss X affirms she has no brain, no nerves, no chest, no stomach, no intestines; there’s only skin and bones of a decomposing body. . . . She has no soul, God does not exist, neither the devil. She’s nothing more than a decomposing body, and has no need to eat for living, she cannot die a natural death, she exists eternally if she’s not burned, the fire will be the only solution for her. (Translation from Cotard 1880)
Cotard explained this delusion as a consequence of a particular type of psychotic depression “characterized by anxious melancholia, ideas of damnation or rejection, insensitivity to pain, delusions of nonexistence concerning one’s own body, and delusions of immortality” (Debruyne et al. 2009, p. 67).
More recently (Gerrans 2000, 2001; Debruyne et al. 2009) the delusion of inexistence has been explained as a consequence of the experience of depersonalisation. The delusion is a personal level response to an intractable and impenetrable loss of affective response to the world. Of course to say that an experience is of depersonalization is not an explanation but an intuitive characterization: the concept expresses the phenomenology of feeling disconnected from the world including one’s own body, as though experiences are “not happening to me”. Such feelings plausibly originate in what we might call affective derealisation: the failure of emotionally salient events to trigger affective responses in the patient so that the world feels strange and unreal. Since affective responses are a form of bodily experience it makes sense that the Cotard delusion is often expressed as beliefs about alteration in body state: in particular that the body is vanishing, disappearing or dead. And since there is an intimate connection between felt body state and self-awareness this loss of normal affective response is expressed as the idea that the self no longer exists.
But surely it is equally intuitively plausible that a person suffering from derealisation might express the experience by saying that the world (perhaps including her body) feels strange, emotionally inert or unreal? In other words, why does the patient not report derealisation, the feeling that the world is unreal? One possible answer is contained in the following suggestion:
Cases of the Cotard delusion have been reported . . . in which the subject proceeds beyond reporting her rotting flesh or her death to the stage of describing the world as an inert cosmos whose processes she merely registers without using the first-person pronoun….The patient does not recognize experiences as significant for her because, due to the global suppression of affect [ex hypothesi a consequence of extreme depression], she has no qualitative responses to the acquisition of even the most significant information. These extreme cases of the Cotard delusion are those in which neural systems on which affect depends are suppressed and, as a consequence, it seems to the patient as if her experiences do not belong to her. Thus the patient reports, not changes in herself, but changes in the states of the universe, one component of which is her body, now thought of as another inert physical substance first decomposing and finally disappearing. (Gerrans 2000)
My earlier self suggested that when the patient experiences global affective suppression she experiences her body as simply a body, a physical substance rather than the body which sustains the self or the body qua self: Hence the depersonalisation. However this simply begs the question. What is it about affective processing which transforms representations of body states to representations of states of a self?