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Capgras syndrome
Capgras syndrome is a delusional misidentification disorder where the patient believes a familiar person (usually a close relative) has been replaced by an identical-looking impostor. It's associated with schizophrenia, dementia, and brain lesions affecting face-emotion processing pathways.
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Capgras syndrome
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Capgras Syndrome
Definition
Capgras syndrome is a delusional misidentification syndrome in which the patient firmly believes that a familiar person - most often a close relative (spouse, parent, child) - has been replaced by an identical-looking impostor. It falls under the category of "Delusions of replacement of significant others" in the classic taxonomy of delusions.
- Kaplan & Sadock's Comprehensive Textbook of Psychiatry (Table 8-2) lists it alongside Clérambault syndrome, Frégoli phenomenon, Othello syndrome, and folie à deux as a classic delusional type.
Classification
Capgras syndrome is a delusional misidentification syndrome (DMS), a subgroup of reduplicative paramnesias - conditions involving the false belief that persons, places, or objects have been duplicated or replaced.
| Syndrome | Core Delusion |
|---|---|
| Capgras | A familiar person has been replaced by an identical impostor |
| Frégoli | Strangers are actually a known person in disguise |
| Cotard | Patient believes they are dead or their body/organs do not exist |
| Reduplicative paramnesia | A place exists simultaneously in two locations |
Neuroscientific Basis (Ellis-Young Model)
This is best understood as the mirror image of prosopagnosia:
- In prosopagnosia: face recognition circuits are damaged, but emotional circuits are intact - the patient cannot consciously identify faces, yet still shows normal autonomic responses to familiar ones.
- In Capgras syndrome: face recognition is intact (the patient can consciously identify the face), but the circuitry mediating the emotional/autonomic response to that face is disconnected.
The result: the patient sees the face of a loved one, but feels no emotional familiarity. The brain then generates a rational-seeming explanation for this mismatch - "this must not really be her; it's an impostor."
"These patients firmly believe that someone close to them, usually a husband or wife, has been replaced by an impostor. They claim that the person, although similar if not identical in appearance, is in fact someone else. Often, this delusion is acted on with the demand that the impostor leave the house."
- Eric Kandel, Principles of Neural Science, 6th ed.
"This explanation implies that Capgras delusions are not the consequence of disordered thinking but of disordered experience... The conclusion that this is not his wife but an impostor is a cognitive response to this abnormal experience, the mind's attempt to explain the experience."
- Principles of Neural Science, 6th ed.
The underlying disconnection is thought to involve disrupted signaling between the fusiform face area (face recognition) and the amygdala/limbic system (emotional tagging of faces).
Etiology and Associated Conditions
Capgras syndrome is not a standalone diagnosis - it appears as a feature of several underlying conditions:
| Category | Examples |
|---|---|
| Psychiatric | Schizophrenia (most classic association), schizoaffective disorder |
| Neurodegenerative | Dementia with Lewy bodies (DLB), Alzheimer's disease |
| Acute/Organic | Delirium (as a form of reduplicative paramnesia) |
| Structural brain lesions | Right hemisphere lesions (especially right temporal/parietal) |
| Other | Corticobasal syndrome (CBS), traumatic brain injury |
In Dementia with Lewy Bodies, common delusions include persecution, phantom boarders, and Capgras syndrome - it is considered part of the typical clinical picture of DLB alongside visual hallucinations and fluctuating cognition.
In delirium, reduplicative paramnesia (including Capgras-type misidentification) arises from decreased integration of recent observations with past memories; delirious patients tend to mistake the unfamiliar for the familiar.
Clinical Features
- The patient recognizes the physical appearance of the person as being very similar or identical to the real person
- Yet maintains the fixed, unshakeable belief that this person is an impostor
- May extend to objects, pets, or even their own reflection
- Can be acted upon - patients may become hostile, aggressive, or demand the "impostor" leave
- The patient can often still identify the person by voice, gait, or clothing (since these cues are processed differently)
Relationship to Other Symptoms
- In schizophrenia, it occurs as a systematized delusion
- In organic brain disease, it often coexists with other neuropsychiatric symptoms (visual hallucinations in DLB, cognitive impairment in dementia)
- It is distinct from pure prosopagnosia (a perceptual deficit) - in Capgras, the recognition failure is emotional/affective, not perceptual
Management
Treatment targets the underlying condition:
- Schizophrenia: antipsychotics (typically atypicals)
- DLB: acetylcholinesterase inhibitors; caution with typical antipsychotics (risk of severe neuroleptic sensitivity)
- Delirium: treat the precipitating cause; low-dose antipsychotics for behavioral symptoms if needed
- Family education is important, as caregivers are often the targets of the delusion and need guidance on de-escalation
Sources: Bradley and Daroff's Neurology in Clinical Practice; Kaplan & Sadock's Comprehensive Textbook of Psychiatry; Kandel's Principles of Neural Science, 6th ed.; Kaplan and Sadock's Synopsis of Psychiatry.
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