4 Classification and assessment in psychiatry4.1 Descriptive psychopathology
4.1 Uncommon psychiatric syndromes
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Written by Resident Doctor Committee · Published
Delusional misidentification syndromes
The delusional misidentification syndromes are defined by a false belief about the identity of a person, the self or a place. Cotard syndrome (nihilism) and erotomania (being loved) fall outside the group.
Syndrome | Belief |
|---|---|
Capgras | A familiar person has been replaced by an identical impostor or double |
Fregoli | Strangers who look nothing like a familiar person are that person, usually a persecutor, in disguise |
Intermetamorphosis | People physically change into one another, in appearance and identity |
Subjective doubles | A double of oneself lives independently |
Capgras syndrome
Capgras syndrome leaves perception and recognition of the face normal, but the person's identity is denied.
It is classed as a variant of reduplicative paramnesia, the belief that a person, place or event has been duplicated.
It occurs in schizophrenia, mood disorders and organic states such as Lewy body dementia, and schizophrenia is the diagnosis most often reported with it.
Prosopagnosia differs because the face itself is not recognised.
Assess threats towards the alleged impostor and consider that person's safety.
Fregoli is the mirror image of Capgras: Capgras denies the identity of a familiar face, while Fregoli finds a familiar person behind strangers' faces.
Intermetamorphosis differs from Fregoli because people are believed to change physically, not to be in disguise.
Reduplicative paramnesia
Reduplicative paramnesia is a fixed, persistent belief that a familiar place has been duplicated, exists in two locations or has been moved, with orientation and recognition of people intact.
It typically follows right hemisphere and frontal damage.
Subtype | Belief | Told apart from |
|---|---|---|
Extravagant spatial localisation | The real current location is a different familiar place | Derealisation, which is only a feeling that surroundings are unreal |
Chimeric assimilation | Two places are fused into one | Confabulation, because the belief is fixed and orientation is intact |
Cotard syndrome
Cotard syndrome is a nihilistic delusion that the self or body does not exist or is dead, or that organs are absent or decayed.
Some patients believe the world no longer exists or that they are unable to die.
It typically occurs in severe psychotic depression in later life, and also in psychosis and neurological disease.
Refusal of food and fluid makes it dangerous, so intake and suicide risk need urgent assessment.
Electroconvulsive therapy (ECT) is considered in severe depressive illness.
Erotomania (De Clérambault syndrome)
Erotomania is the fixed belief that a person of higher status, usually barely known or never met, is secretly in love with the patient.
Patients reread rebuffs as proof of love and may perceive coded messages.
Being a delusion, it arises in psychotic, affective, organic and substance-related disorders, but not in neurotic disorders with intact reality testing.
Ask about unwanted contact, stalking, threats and perceived rivals.
Othello syndrome (morbid jealousy)
Othello syndrome is a fixed, unfounded conviction of a partner's infidelity, held against evidence, with checking, searching and following.
Morbid jealousy can be a delusion, an overvalued idea or an obsession, and can stand alone as a delusional disorder.
It is defined by its content (infidelity), so it is not a misidentification syndrome.
It is more common in men and is associated with alcohol dependence, and organic causes and drugs also produce it.
It is dangerous to the partner and is not cured by separation, which can raise the danger.
Assess domestic abuse, weapons, previous violence and suicide risk, and involve safeguarding.
Folie à deux
Folie à deux (induced or shared delusional disorder) is the sharing of similar delusions by two or more closely connected people.
The shared content is most often persecutory, religious or grandiose.
Separation may help some cases but is neither a diagnostic test nor a complete treatment.
Delusional infestation (Ekbom syndrome)
Delusional parasitosis (Ekbom syndrome, delusional infestation) is a fixed, false conviction of being infested despite normal examination and investigations.
Patients often bring a specimen of supposed parasites or fibres, the matchbox sign.
The fixed belief defines it, not the formication (crawling sensations) that may accompany it.
Patients are usually first seen in dermatology, because the complaint and the self-inflicted lesions are on the skin.
Secondary delusional infestation arises from psychotic illness, organic brain disease, toxic or confusional states (alcohol or stimulant withdrawal, delirium) and systemic illness.
It has no recognised link to neurodevelopmental conditions.
Exclude genuine infestation, skin disease, neuropathy and substance effects, and acknowledge suffering without endorsing or confronting the belief.
Somatic and dissociative syndromes
Syndrome | Features |
|---|---|
Couvade syndrome | Genuine pregnancy-like symptoms in an expectant father, starting with his partner's pregnancy and usually settling after the birth |
Pseudocyesis | A woman's firm belief that she is pregnant, with objective pregnancy-like signs and negative pregnancy tests |
Anton's syndrome | Cortical blindness after bilateral occipital infarction, with denial of the loss and confabulation of what is seen |
Diogenes syndrome | Severe self-neglect and domestic squalor in an older person living alone, with hoarding, refusal of help and no concern |
Couvade is a non-delusional, conversion-type presentation, whereas pseudocyesis rests on a firm belief of pregnancy.
Diogenes syndrome often affects people of previously good standing.
Ganser syndrome
Ganser syndrome features approximate answers (vorbeireden), which show the question has been understood, such as giving a nearly correct number.
Approximate answers are a disorder of the form of thought, and they are not deliberate.
The syndrome is described in prisoners awaiting trial, though it is not confined to custody, with clouding of consciousness and pseudohallucinations.
It is classed with the dissociative disorders.
It ends abruptly and leaves amnesia for the period of illness.
Factitious disorder and malingering
Presentation | How symptoms arise | Motive |
|---|---|---|
Factitious disorder | Deliberate falsification or induction of illness | To occupy the sick role, with no external incentive |
Malingering | Deliberate exaggeration or fabrication | An obvious external incentive such as avoiding work, money or legal advantage |
Somatic, dissociative and health-anxiety disorders | Symptoms are not intended | Symptoms and distress are experienced as real |
Delusional disorder | Belief is sincerely held | No falsification |
Munchausen syndrome is the chronic form of factitious disorder, with repeated presentations and operations.
In the International Classification of Diseases, 11th revision (ICD-11), the Munchausen eponyms map onto factitious disorder, with a separate code for the form imposed on another (proxy).
Body integrity dysphoria is a lifelong sense that a limb does not belong, whereas factitious disorder pursues the patient role.
Motor neurone disease is purely motor, so objective sensory loss with no anatomical pattern points to a functional or feigned presentation.
Absence of a medical explanation is not evidence of factitious disorder.
Pseudologia fantastica
Pseudologia fantastica (pathological lying) is fluent, elaborate, self-aggrandising lying, told as if believed and dropped when disproved.
It is a feature of Munchausen syndrome, and factitious disorder has been proposed to be a narrower, illness-focused form of it.
It differs from delusion, which persists against disproof, and is distinct from confabulation.
Culture-bound syndromes
Culture-bound syndromes (cultural concepts of distress) are patterns of distress shaped by a particular culture, recognised by the symptom pattern together with the culture and geography where they are described.
Rare syndromes found in all populations are uncommon but not culture-bound.
Culturally shared beliefs are not automatically delusions, but coexisting anxiety, depression, psychosis or physical illness still needs assessment.
Asia
Syndrome | Where | Features |
|---|---|---|
Amok | Malay peoples, Philippines | Mostly men: brooding after a slight or loss of face, then a sudden indiscriminate violent frenzy, then exhaustion or stupor with amnesia |
Latah | Malaysia, Indonesia | Mostly middle-aged women: exaggerated startle with echolalia, echopraxia, automatic obedience and sometimes coprolalia, leaving embarrassment rather than danger |
Koro | Called suo yang in southern China | Acute panic that the penis is retracting into the body, with the belief that full retraction will be fatal |
Dhat | South Asia | Fatigue, weakness, poor concentration and low mood or anxiety blamed on loss of semen, often in the urine |
Taijin kyofusho | Japan | Fear that one's gaze, odour, blushing, body or behaviour will offend or embarrass others, leading to social avoidance |
Khyal cap ('wind attacks') | Cambodia | Panic-like attacks from the belief that khyal, a wind-like substance, rises with the blood and threatens fainting, stroke or death |
Taijin kyofusho is other-directed: the fear is of offending or embarrassing other people.
Africa, the Americas and the Arctic
Syndrome | Where | Features |
|---|---|---|
Brain fag | West Africa (Nigeria) | Students under academic strain: poor concentration and retention, head and neck burning, crawling sensations, blurred vision and anxiety |
Kufungisisa | Shona people, Zimbabwe | 'Thinking too much': dwelling on troubles is believed to cause psychological and bodily symptoms |
Ataque de nervios | Caribbean Latino people | Abrupt screaming, trembling and aggression after a family crisis, ending in collapse, patchy amnesia and relief |
Susto | Latin America | Illness blamed on a fright that drove the soul from the body, with poor sleep and appetite, low mood and lethargy for months or years |
Maladi moun | Haiti | Illness sent by another person out of envy or malice |
Piblokto (Arctic hysteria) | Inuit | Abrupt dissociative frenzied excitement, sometimes followed by convulsions and sleep, with amnesia afterwards |
Windigo (witiko) psychosis | Algonquian-speaking peoples | Belief that one is becoming a cannibal monster, classically in a famine winter |