Jules Côtard (1840–1889) presented a report entitled, ‘Du délire hypochondriaque dans une forme grave de la mélancoli anxieuse’, in he described a 43-year-old female patient on 28 June 1880 at a meeting of the Societé Médico-Psychologique. The woman believed that she had ‘no brain, nerves, chest, or entrails, and was just skin and bone … that neither God or the devil existed … and that she was eternal and would live forever’ (Berrios & Luque, 1995, p. 218). In addition, she said that she did not need food and asked to be burnt alive. She had made various suicide attempts. Côtard initially diagnosed lypémanie and formed the view that this was a new type of lypémanie consisting of anxious melancholia, ideas of damnation or possession, suicidal behaviour, insensitivity to pain, delusions of non-existence and delusions of immortality.

In the preceding chapters, I focused on the psychopathology of perception or of sensation. These pathologies often, if not invariably, are recognized as indicating underlying disorders or diseases. I now turn to synaesthesia, a condition that is not usually thought of as a disorder or disease but rather as a variant of normal experience. Put simply, it is the merging of the senses, in which a stimulus in one sensory modality both evokes a normal perception, as expected, in the same modality and an anomalous perception in another modality. In other words, there is cross-modal perception.

The nature of the self is essential to an understanding of the conditions described in this section. For Jaspers (1997), the self has four formal characteristics, namely (1) the feeling of activity, that is, an awareness of being active; (2) awareness of unity; (3) awareness of identity; and (4) awareness of being distinct from an outer world and all that is not self. The awareness of activity depends upon kinaesthetic information from our joints and muscles and proprioceptive information regarding the position of bodies in space. In addition to these two sensory modalities, the other senses, including vision, hearing and touch, also contribute to our knowledge of being active. Thus, sensory data play a significant role in the definition of the body schema, in the manner in which our body exists in space and how it is engaged in particular activities. It is plain from the preceding that the awareness of activity is derived from our being embodied such that it is difficult to imagine a sense of activity of the self without corporeality. I discuss embodiment and the abnormalities of the body in the next section.

Macmillan and Shaw (1966, p. 1032) ntroduced the term senile breakdown to describe

a small group of individuals who cease to maintain the standards of cleanliness and hygiene which are accepted by their local community. … The usual picture is that of an old woman living alone, though men and married couples suffering from the condition are also found. She, her garments, her possessions, and her house are filthy. She may be verminous and there may be faeces and pools of urine on the floor.

The conditions described in this chapter are distinct from those in the preceding chapters in this section on disorders of perception in that both vulvodynia and penoscrotodynia are disorders of sensation rather than of perception. The distinction that I seek to draw is that between sensation and perception. Sensation is the first stage in receiving information outside the self. The sensory system includes the visual, auditory, tactile, olfactory, gustatory, kinaesthetic and proprioceptive pathways. These pathways deal with the receipt, transformation and transmission of raw and disparate sensory data from peripheral receptors to the central nervous system (CNS). The transformation of raw sensory stimuli into sensory information is then decoded into meaningful perception involving active processes that are influenced by attention, affect, cultural expectations, context, prior experiences, memory and prior concepts (Oyebode, 2018). What is important is to recognize that such a distinction exists between the awareness of primary sensations and the awareness of perceptions.

Ekbom syndrome, or delusional infestation, is a condition that sits between disorders of thinking, namely delusions, and disorders of perception, namely hallucinations. It is defined by Skott (1978, p. 11) as ‘a persistent condition in which the patient believes that small animals such as insects, lice, vermin or maggots are living and thriving on or within the skin. In spite of all negative evidence to the contrary, the patient has a firm conviction that she/he is infested. This belief, if unshakeable, is best characterized as a primary delusion. It is an isolated phenomenon without relation to other psychotic symptoms.’ Skott makes the point that this condition has had a variety of names dating back to Thirbierge in 1894, who termed it acarophobia, and in the English language literature, terms include acaraphobia, dermatophobia, parasitophobia, delusion of parasitosis, delusion of dermal parasitosis and delusions of infestation.

Olfactory reference syndrome was codified as a condition worthy of attention by Pryse-Phillips in his seminal paper published in 1971 (Pryse‐Phillips, 1971). He described 36 patients presenting with the belief that smells emanated from their bodies without the intervention of any external agency, what Pryse-Phillips termed intrinsic hallucinations. This belief was accompanied by a ‘contrite’ reaction manifest as a deep sense of shame, embarrassment and self-abasement and sensitivity to the reaction of people around them. There were also behavioural responses to this belief, including excessive washing, excessive changing of clothing and social withdrawal. This condition was distinguished from olfactory hallucinations in the context of schizophrenia, mood disorder and epilepsy.

The nature of the self depends on at least four presuppositions, namely a subjective awareness of activity, a subjective awareness of a sense of unity of self over time, an awareness of a persisting and singular identity over time and, finally, a distinct sense of being separate from other material objects and other selves. In this chapter, I deal with two conditions, possession states and dissociative identity disorder (multiple personality disorder), both of which seem to undermine the presupposition that the sense of self is predicated upon a unified sense of self over time and a sense of a persisting and singular identity over time.