Incubus Syndrome: A Case Series and Review of Literature

Abstract

Incubus syndrome, characterized by delusional belief in female patients of being sexually approached by an unforeseen person, is rarely described in literature and description has been limited to isolated case reports. We describe four patients with schizophrenia, who reported the phenomenon of incubus and responded well to treatment with antipsychotics. A review of literature yielded five reports (describing six cases), most of which were described in the context of schizophrenia.

INTRODUCTION

The term incubus syndrome is used for a rare form of delusion in which patients harbor a delusion that they have been sexually approached by an unseen lover.[1] It is considered a type of the secondary erotomania, in which the persons have delusion of being raped by an imaginary lover.[2,3,4,5]

The description of incubus syndrome is limited to few case reports. We describe four cases who presented with delusions amounting to incubus syndrome.

CASE REPORTS

Case 1

A 58-year-old married female who was suffering from hypertension and diabetes mellitus since the age of 52 years presented with a history of abnormal experiences since the last 12 months. All her symptoms started after a huge financial debt. Initially, her symptoms were characterized by delusion of persecution and reference. After 3–4 months of onset of psychotic symptoms, in addition to the delusion of persecution and reference, she developed symptoms suggestive of incubus. As per the patient, while she would go to sleep at any time of the day or night, she would have experience of someone having sexual intercourse with her. Often, she would wake up in the middle of the sleep (i.e., after few hours of sleep) and feel that someone had sexual intercourse with her. As per patient while lying down, she could feel that someone was touching her all over the body including the breast and genitalia. In addition, she would be able to feel a pressure over her body as if someone was lying on her body and at the same time would be able to feel the to and fro motion of the phallus in her genitalia. On waking up, she would not be able to find anyone and would not be able to go back to sleep. She would not be able to pinpoint the person having sexual intercourse with her, but was fully convinced about the experience which she would have every day. She denied of having orgasm during any such episodes. She held this belief with conviction, amounting to delusion. She attributed her belief to black magic and demons. This was associated with a significant distress. This experience was not associated with any other sleep-related disorder or experiences. Over the period in addition to the above symptoms, she also developed delusion of control and somatic passivity. There was no history suggestive of any other psychiatric symptoms, any neurological deficits, symptoms suggestive of narcolepsy, insomnia, hypersomnia, sleep terrors, nightmares, sleep-related movement disorders, panic attacks, posttraumatic stress disorder, any cognitive deficits, and recent change in medications. Her sexual history revealed that she was sexually inactive for the past few years and mostly would sleep alone.

Her routine investigations in the form of hemogram, renal function test, liver function test, serum electrolytes, thyroid function test, and magnetic resonance imaging of brain did not reveal any abnormality. Based on the available information, she was diagnosed with late-onset schizophrenia and was started on olanzapine 10 mg/day which was increased to 15 mg/day. Over the period of 3 months, all her symptoms resolved. Later, she also developed postpsychotic depression and required the use of venlafaxine. After remission of depressive symptoms, she maintained well on olanzapine for the next 3 years. After this, she stopped olanzapine and maintained well without medications for the next 6 years and again had a relapse of similar symptoms following a stressor. She was again managed with olanzapine and achieved remission in 4 months.

Case 2

A 24-year-old graduate, single, female presented to emergency department after a suicidal attempt. Exploration of history revealed that she was symptomatic since the age of 20 years. Her illness had an acute onset and was continuous in course. The symptoms were characterized by auditory hallucinations of commenting and discussing type, suspiciousness, delusion of reference, delusion of persecution, delusion of control, thought echo, remaining aloof, apathy, anhedonia and poor self-care, and marked psychosocial dysfunction. After about 3 years of onset of symptoms in addition to the aforementioned symptoms, additionally she started claiming herself to be incarnation of a goddess and reported that she was approached at the night time by a male god for sexual intercourse. She would elaborate that, whenever she would go to bed, she would be able to feel the presence of male god, whom she could feel over her body. She could also feel her legs being separated, would be able to feel movement of the hands over her body, and would be able to feel the movement of phallus in her vagina. Corroborative evidence from the family members (who would share bed with her) confirmed patient making pelvic movements at night which was not associated with any genital self-stimulation. These would mostly occur after 1–2 h of sleep, but there was a wide variation in timing with respect to sleep onset and these experiences. She held this belief with full conviction. She denied of having orgasm during any such episodes. The patient was not distressed by these symptoms, rather would enjoy this experience. Over the years, she had received adequate trials of olanzapine, aripiprazole, and risperidone without much benefit. Under the influence of auditory hallucinations, she jumped from the roof top and landed in emergency. She sustained multiple fractures of both lower limbs. Initially, she was managed by the orthopedicians for her fracture and was clinically stabilized and then transferred to psychiatry inpatient unit. There was no history suggestive of any neurological deficits, narcolepsy, insomnia, hypersomnia, sleep terrors, nightmares, sleep-related movement disorders, panic attacks, posttraumatic stress disorder, any cognitive deficits, and substance abuse. Her routine investigations in the form of hemogram, renal function test, liver function test, serum electrolytes, thyroid function test, and magnetic resonance imaging of brain did not reveal any abnormality. She was diagnosed with paranoid schizophrenia. She was managed with electroconvulsive therapy and clozapine, with which all her positive symptoms resolved. She also perceived significant improvement in the negative symptoms. She maintained well for the next 1 year on clozapine, without any relapse of symptoms.

Case 3

A 45-year-old woman presented to the emergency department with organophosphorus poisoning. Evaluation of history revealed that she was suffering from a psychotic disorder since the age of 25 years. Her illness was characterized by delusion of reference, delusion of persecution, delusion of control, poor socialization, poor self-care, anhedonia, and apathy. Since the age of 36 years in addition to the aforementioned symptoms, she started to experience that someone was having sexual intercourse with her. As per patient while lying down, both during the daytime and night, she could feel that someone was touching, kissing her all over the body including the breast, lips, and genitalia. Often, she would wake up in the middle of the sleep (after few hours of going to sleep) and feel that someone had sexual intercourse with her. She held this belief with delusional conviction. She would attribute these experiences to black magic. She would remain very distressed due to these symptoms and would feel guilty, as it was against her sociocultural belief to have sexual intercourse with someone other than her spouse. She never experienced orgasm during any such episodes. Due to this, she also attempted to harm herself on multiple occasions. After one of the self-harm attempt, she came to the emergency department. There was no history suggestive of any neurological deficits, narcolepsy, insomnia, hypersomnia, sleep terrors, nightmares, sleep-related movement disorders, panic attacks, posttraumatic stress disorder, cognitive deficits, and substance abuse. Her investigations in the form of hemogram, renal function test, liver function test, serum electrolytes, thyroid function test, and magnetic resonance imaging of brain did not reveal any abnormality. She was diagnosed with paranoid schizophrenia and was managed with risperidone 3 mg/day, with which her symptoms resolved.

Case 4

A 52-year-old female was diagnosed with hypertension, diabetes mellitus, hypothyroidism, and obesity at the age of 45 years. From the age of 47 years, gradually she developed symptoms in the form of delusion of control, thought echo, auditory hallucinations of commenting and commanding in nature, aloofness, irritability, and poor self-care. In addition, she would also report of being raped while she goes to sleep. She would remain fearful because of the same. She would describe her helplessness and say that whenever she would go to bed, she would feel sensation over her genitals and breasts suggestive of someone having sexual intercourse with her. She would clearly describe that, after few hours of going to sleep, she would feel that someone would come and lie down over her, move his hands over her body, especially the breast and genitalia, and have penetrative intercourse with her. However, she would deny ever having orgasm during such episodes. She held this belief with conviction, amounting to delusion. There was no history suggestive of any neurological deficits, other sleep-related phenomenon, panic attacks, posttraumatic stress disorder, and substance abuse. On investigation, no abnormality was found in her hemogram, renal function test, liver function test, serum electrolytes, thyroid function test, and magnetic resonance imaging and electroencephalogram. She was treated with tablet haloperidol and electroconvulsive therapy. She showed significant improvement in all her symptoms.

DISCUSSION

According to mythological beliefs, an incubus is a Lilin-demon in male form, who lies upon women with the intent of having sexual activity. The female counterpart of incubus is understood as succubus.[6] The person attempting to have sexual intercourse is culturally believed to be sex demon.

The earliest description akin to incubus in published literature is attributed to a Dutch physician's collection of case histories, published in 1664. In these case histories, patients described themselves to be sexually approached, and during such acts, they were hardly able to respond.[6] Over the years, many similar descriptions are available which can be understood as nightmares or sleep paralysis.[6]

A PubMed search with key word of “incubus syndrome,” yielded only three case reports[1,7] and one article discussing the phenomenon in relation to sleep.[6] We could additionally locate two case reports in Google search[8,9] and one possible case described as having erotomanic delusions with somatic sexual hallucinations.[10]

In one of the reports, authors described two cases in which patients had delusions of been sexually approached at night by an unseen lover. These patients were diagnosed with schizophrenia based on the whole clinical picture.[1] In another case report, authors described the co-occurrence of incubus and Capgras syndrome.[7] In addition, we came across another case report in which authors described a patient with erotomanic delusions with somatic sexual hallucinations in an elderly woman.[10] Google search yielded few more case reports. In a case report from India, authors described the phenomenology of incubus in a patient with schizophrenia who required the use of electroconvulsive therapy.[9] Another case report from Iran documented the phenomenon of incubus during the prodromal phase or as a precursor of schizophrenia in a 23-year-old female with schizophrenia.

Three out of the four of our cases were diagnosed with schizophrenia, and one of them was diagnosed with persistent delusional disorder. Most of the reported cases in literature have also been diagnosed with schizophrenia.[7,8,9,10,11] Similar to the earlier reported cases, our patients also responded well to treatment. However, the unique manifestation in the first case was recurrence of phenomenon in both the episodes of illness. Two out of four patients in our case series ascribed their symptoms to black magic, and one patient ascribed the phenomenon to god. These descriptions suggest that cultural beliefs play an important role in the formation of such delusions.

In recent times, people have tried to understand the experiences akin to incubus, as manifestations of nightmare and sleep paralysis.[6] Sleep paralysis is understood as a parasomnia, in which the sufferer is unable to move his or her body. Mostly, this phenomenon is seen at the sleep onset or at the time of waking up and is understood as occurrence of “atonia,” when the person is awake, aware about what is happening to them, and this can last for few seconds to minutes. Sleep paralysis is considered to peak around the age of 30 years and appears to be associated with psychiatric disorders such as posttraumatic stress disorder, narcolepsy, and panic attacks.[6] None of our patients had any of such comorbidities. All our patients had delusional beliefs of having such experiences; such delusional beliefs occurred as part of the psychosis, such delusional beliefs usually followed development of other delusions by months to years, symptoms started in 5^th or 6^th decade in three out of the four patients, and all our patients responded to treatment of their primary psychiatric disorders, i.e., psychosis. This possibly suggests that the phenomenon reported by our patients was that of incubus. Further, three out of the four patients reported the presence of delusion of control in addition to the phenomenon of incubus. This possibly suggests that there could be some relationship of delusion of control with incubus and it may be some kind of extension of delusion of control related to sexual phenomenon or sleep-related phenomenon.

Our cases add to the limited literature on incubus syndrome and suggest that patients manifesting with such phenomenon must be evaluated further for the cultural explanations for their symptoms.

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Conflicts of interest

There are no conflicts of interest.