Capgras syndrome
Capgras syndrome, or the Capgras delusion, is a rare psychiatric disorder characterized by the belief that a close friend or family member has been replaced by an identical impostor. This condition involves a conflict of recognition, where the individual can see and interact with the person but does not recognize them as the same individual. The syndrome is not limited by age, gender, or culture, affecting people universally. The underlying causes are thought to involve organic disturbances in the brain, particularly in areas associated with facial recognition. Neurological conditions such as Alzheimer’s disease, epilepsy, and various types of brain lesions have been linked to the onset of this delusion. While there’s no standardized treatment, some individuals have shown improvement with antipsychotic or antidepressant medications, alongside cognitive techniques like reality testing. Historically, explanations for Capgras syndrome have evolved from psychoanalytic interpretations to neurocognitive models, reflecting a shift in understanding its origins and mechanisms. The complexity of this delusion underscores the intricate relationship between perception, recognition, and emotional response.
Capgras syndrome
Disease/Disorder
Also known as: Capgras delusion
Anatomy or system affected: The pathway connecting the ventral stream to the limbic system; the patient's belief evaluation system
Definition: The delusional belief that at least one family member, friend, or significant other has been replaced by an impostor
Key terms:
circumscribed: not impacting on the patient's other beliefs, meaning that these other beliefs are not adjusted
delusional misidentification: a delusional belief about the identity of an individual or thing such that the individual or thing is misidentified (e.g., that different people are the same person in disguise [Frégoli delusion] or that one's wife is an impostor)
monothematic: restricted to one type of belief or theme, rather than expanding to include multiple themes
skin conductance response / galvanic skin response: a change in the skin's ability to conduct electricity owing to increased or decreased sweating brought on by changes in autonomic arousal
Causes and Symptoms
The Capgras delusion represents one of several rare psychiatric disorders that share a common theme: that of delusional misidentification. A typical claim made by the Capgras patient is that one or more close relatives, friends, or significant others have been replaced by exact doubles. The belief that the person (or people) in question has been replaced indicates that the patient does not perceive both individuals simultaneously; the real person is always perceived to be absent, leaving just a single, identical impostor. The Capgras delusion is universal, in that similar delusional beliefs occur in individuals from all cultures. It affects both sexes and can strike at any age from adolescence on.
Within the Capgras patient there appears to exist a conflict of recognition, a seeming paradox in which the object of perception (the significant other) is and yet is not recognized by the patient. Physically, the “impostor” is said to be just like the real person, down to their mannerisms and voice patterns, but is not recognized as being that person.
The disorder is not the result of some global perceptual problem, nor is the “impostor belief” ubiquitous; the patient correctly identifies and believes in the authenticity of the vast majority of other people. Instead, the delusion is specific, directed only toward persons of significance, and is monothematic and circumscribed.
Over the years, more and more evidence has been amassed implicating some form of organic disturbance in the etiology of the Capgras delusion. One study, published in 1994, found that 35 percent of Capgras cases had some sort of organic cause or aggravating factor, such as a lesion in the brain's left temporal or right frontal lobe. Other cases have been associated with neurological conditions such as epilepsy, cerebrovascular disease, certain types of brain tumor, and certain neurodegenerative diseases, particularly Alzheimer's disease and dementia with Lewy bodies.
More recent explanations of the Capgras delusion have tended to be based on a neurological disturbance within the face-recognition system. According to an established account of normal facial recognition, when presented with a familiar face, the brain's face-recognition unit triggers information stored in person identity nodes. In simple terms, this enables overt or conscious identification of the face. In addition, there exists a separate pathway connecting the ventral stream to the limbic system, particularly the amygdala. In the presence of familiar faces, heightened arousal occurs, as indicated by an increase in skin conductance response (SCR), also known as the galvanic skin response (GSR) or the psychogalvanic reflex (PGR). This is often interpreted as a measure of covert recognition. The mirror-image model proposes that Capgras patients have an intact overt recognition system but a dysfunctional covert system. In other words, the patient can identify a familiar face, but that recognition does not trigger heightened autonomic arousal, and there is no increase in SCR. As an aside, patients with prosopagnosia, who are unable to consciously recognize familiar faces, do show increased SCR when in the presence of familiar faces; they are believed to have a dysfunctional overt pathway and a functioning covert pathway, the reverse of the Capgras patient—hence, the “mirror-image model.”
Contemporary accounts of the Capgras delusion tend to involve either one or two explanatory stages. One-stage models hold that the neurological disturbance, in the otherwise rational individual, results in an anomalous experience. In the presence of his or her spouse, for example, the patient feels that something is wrong, and this oddness is explained by forming the impostor belief. Two-stage models, in contrast, maintain that the anomalous experience is not sufficient to form the delusional belief and that there must also be a disruption in the patient's belief-evaluation system (or some other form of cognitive disruption, such as attributional bias). It is the combination of first-stage neurological disturbance and second-stage cognitive disruption that produces the impostor belief.
Treatment and Therapy
There is no single recognized treatment for the Capgras delusion. Treatment and therapy is often determined on an individual case-by-case basis. Case-study reports indicate the successful use of antipsychotic drugs (such as olanzapine, pimozode, and prophylaxis) or antidepressants (mirtazapine). Cognitive techniques such as reality testing may also prove successful. The Capgras delusion can also prove resistant to treatment.
Perspective and Prospects
Prior to the aforementioned one- and two-stage accounts and the mirror-image model, the psychoanalytic approach sought to explain the Capgras delusion in terms of splitting the significant other into real and false personae. The patient's act of splitting was said to be symptomatic of their ambivalence toward the significant other. The Capgras delusion was therefore seen as a way of resolving the love-hate conflict underlying this ambivalence. The son can direct hostile feelings toward his mother, for example, if he believes that she is really an impostor. He is thus free to express his aggression without experiencing any guilt.
This psychoanalytic approach has largely been discredited. Capgras delusion has thus been transformed from a psychoanalytic disorder of function, stemming from an unconscious conflict and a means of resolving it, to a neurocognitive disorder. More recent discussions on the delusional state have centered on the extent to which those processes that bring about the delusional belief occur subpersonally (below conscious awareness) and thus do not involve, or even require, anomalous patient experience.
Bibliography
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