Summary
The very rare Capgras syndrome, in modern manuals inserted between the atypical psychotic disorders, is the delusional belief of existence of “duplication” of other people (significant in patient’s life), of the patient, or both of them. All this is usually inserted into a persecutory delusion and the double often assumes threatening and hostile aspects.
To date the neurochemical basis and neuronal commitment that allow the appearance of this particular delusion are not known, but several biological and neuropsychological hypotheses, very fascinating to be taken into consideration, have been made. As in many other areas, the relationship between organic and functional components is thin and complex. The organic nature can not be ignored or excluded.
The Capgras syndrome may occur in a wide range of ages and in a variety of psychiatric disorders. The most commonly seen diagnosis in patients with the delusion of doubles is, anyway, schizophrenia, particularly paranoid schizophrenia.
Several psychological mechanisms underlying the Capgras delusion have been proposed: depersonalization combined with a feeling of unreality; a disorder of the intuitive feeling of familiarity; realization of a wish; regression to archaic mental processes; disturbed perception; an important effort in tackling strong and ambivalent feelings; an attempt to mask incest feelings or homosexuality. From the psychodynamic point of view, several authors assumed that the Capgras syndrome can represent a psychotic solution of ambivalence feelings. It is speculated that there are two main opposed visions of the same person and the invention of the double allows the patient to express hostility without risking the feeling of guilt that might arise by the expression of negative manifestations directed against affectively significant individuals. It was therefore argued that the origins of this ‘doubling’ of the object appear to reside in the unacceptable patient’s ambivalence toward the significantly love object. The internalized object representations, split into “good” (conscious) and “bad” (unconscious), persist until an event causes a significant change in interpersonal affective relationships. Repressed feelings become aware, “bad” images emerge, and the patient would begin to assert that an emotionally significant person is not what it seems but a double lookalike. The patient then let start the defense mechanism of splitting and concludes that the person who elicits such feelings is not the person previously known and loved, but an impostor, a double.
It has also established the prevalence of organic causes of Capgras syndrome in a wide range of favoring conditions, some general (as an organic brain syndrome), some specific (such as lesions). In patients with Capgras delusion were then noticed several organic links: poisoning by drugs, reaction to metabolic disorders, relationships with neurological disease, cortical atrophy, multiple sclerosis, cerebral hematoma, senile dementia, post-traumatic encephalopathy, etc.
To date, however, the neurochemical basis and the neuronal engagement which allow the event remain unknown.