There is a scenario that seems like a suspense script, but it is a daily reality for some people: waking up and being absolutely certain that the loved one has been replaced by an imposter. Although the appearance, voice, and gestures are identical, the individual feels that it is not the same person. When other people try to refute this belief, the situation worsens, generating doubt about the reliability of everyone around them.
This clinical picture corresponds to Capgras Syndrome, an uncommon condition, but one that affects about 16% of individuals diagnosed with Alzheimer's disease. It can coexist with other neurological and psychiatric conditions, being primarily characterized by the paranoia that a loved one is a fraudulent substitute.
Clinical signs include agitation, irritability, refusal to interact with the supposed imposter, and rejection of any proof that the person is genuine, focusing intensely on 'exposing' the individual. Due to the conviction that the 'imposter' intends to cause harm, the patient may exhibit hostility and aggression towards the other person.
A 2019 study indicated that, although most cases of Capgras do not result in acts of violence, there is a strong correlation between this syndrome and violent episodes. This link is accentuated in the presence of aggravating factors, such as substance use, social isolation, and a previous history of aggressiveness. Furthermore, a relationship between Capgras and cases of self-harm was observed.
Scientists have not yet precisely defined the mechanism that triggers Capgras syndrome, which was first studied academically in the 1920s. However, it is known that it is related to brain lesions caused by various pathologies, including Alzheimer's (and other forms of dementia), schizophrenia, Parkinson's, epilepsy, pituitary gland tumors, and others.
Research suggests that damage to the bilateral frontal areas, the right limbic system, and the temporal regions of the brain may be responsible for the syndrome. A widely accepted theory suggests that these lesions compromise the connection between the visual recognition of a face and the emotional response usually associated with it. Consequently, the patient identifies the appearance but fails to feel the expected affective familiarity, interpreting the person as a fraud. One piece of data supporting this hypothesis is that Capgras patients perceived the impostors when they were physically present, but not when contacted by phone.
The diagnostic process requires imaging tests, such as MRI and CT scans, to assess brain changes. Capgras symptoms can be alleviated by using antipsychotic medications; however, the definitive solution lies in eliminating the underlying cause, which is not yet possible in cases like Alzheimer's disease.
This implies that the patient will likely require continuous care. The family must adapt to this new reality, seeking ways to maintain closeness with the patient, since the distrust that one or more relatives are fake may persist or resurface over time. A recommended strategy is to announce the presence verbally before the patient sees the person, aiming to establish a connection without depending on visual stimuli.
Capgras Syndrome belongs to a group of neurological and psychiatric disorders called delusional misidentification syndromes. In these conditions, the individual holds a delusional belief that people, places, objects, or even their own identity have been altered. Even recognizing the physical appearance, they mistakenly interpret who or what they are seeing, maintaining this conviction despite contrary evidence.
Other conditions in this group include: Fregoli Syndrome, where the patient believes an unknown person is actually a known person who constantly changes appearance; Metamorphopsia, where the patient does not associate physical appearance with identity, believing acquaintances have changed identities; Subjective Doppelgänger Syndrome, characterized by the belief in doppelgängers with distinct lives and personalities; Clonal Pluralization, which involves the belief in copies of oneself with personality similarities; Misidentification of one's own reflection, where the reflection in the mirror is seen as a stranger; Delusional Companion Syndrome, in which inanimate objects are considered sentient and emotional beings; Reduplicative Paramnesia, which occurs when a familiar place is perceived as duplicated or displaced.
