[8] It presents often in individuals with a neurodegenerative disease, particularly at an older age;[9] it has also been reported as occurring in association with diabetes, hypothyroidism, and migraine attacks.
[13] They described the case of a French woman, "Madame Macabre," who complained that corresponding "doubles" had taken the places of her husband and other people she knew.
[5] Capgras and Reboul-Lachaux first called the syndrome "l'illusion des sosies", which can be translated literally as "the illusion of Doppelgänger.
It was not until the 1980s that attention turned to the usually co-existing organic brain lesions originally thought to be essentially unrelated or coincidental.
Today, the Capgras syndrome is understood as a neurological disorder, in which the delusion primarily results from organic brain lesions or degeneration.
At the time of her admission earlier in the year, she had received the diagnosis of atypical psychosis because of her belief that her husband had been replaced by another unrelated man.
She refused to sleep with the impostor, locked her bedroom and door at night, asked her son for a gun, and finally fought with the police when attempts were made to hospitalise her.
A 66‐year‐old European New Zealand man was referred for inpatient evaluation and treatment by his psychiatric consultant due to suicidal ideation, low mood, and delusions about his wife.
A mental state examination demonstrated evidence of impaired perception, complex visual hallucinations, and delusions about his wife.
Investigations including routine blood tests, ECG, and brain computed tomography (CT) scan were all unremarkable.
[20] The following case is an instance of the Capgras delusion resulting from a neurodegenerative disease: Fred, a 59-year-old man with a high school qualification, was referred for neurological and neuropsychological evaluation because of cognitive and behavioural disturbances.
In a 1990 paper published in the British Journal of Psychiatry, psychologists Hadyn Ellis and Andy Young hypothesized that patients with Capgras delusion may have a "mirror image" or double dissociation of prosopagnosia, in that their conscious ability to recognize faces was intact, but they might have damage to the system which produces the automatic emotional arousal to familiar faces.
In 1997, Ellis and his colleagues published a study of five patients with Capgras delusion (all diagnosed with schizophrenia) and confirmed that although they could consciously recognize the faces, they did not show the normal automatic emotional arousal response.
[2] William Hirstein and Vilayanur S. Ramachandran reported similar findings in a paper published on a single case of a patient with Capgras delusion after brain injury.
[34] Hirstein explained the theory as being "a more specific version of the earlier position I took in the 1997 article with V. S. Ramachandran," and elaborated: According to my current approach, we represent the people we know well with hybrid representations containing two parts.
[38] Many have argued for the inclusion of the role of patient phenomenology in explanatory models of the Capgras syndrome in order to better understand the mechanisms that enable the creation and maintenance of delusional beliefs.
Diagnosis is primarily made on a psychiatric evaluation of the patient, who is most likely brought to a psychiatrist's attention by a family member or friend believed to be an imposter by the person under the delusion.
[45] Typically, treatment of delusional disorders is challenging due to poor patient insight and lack of empirical data.
[4] A study has shown that using medications appropriately to target the underlying disorder's core symptoms can be an effective management strategy.