Capgras delusion is a psychiatric condition in which the patient believes that someone has been replaced by an identical double. The double usually replaces someone close to the patient, such as a family member or friend. This condition usually occurs in the form of a symptom of a psychiatric or medical problem, such as schizophrenia or brain injury, and it is more common in women than in men.
The name for this condition comes from the French psychiatrist who first documented a case of Capgras delusion in a young woman in the 1920s. Numerous cases have been documented since this period, and there is historical evidence that Capgras delusion was probably present in many ancient societies as well. The myth of the changeling which is common to many cultures is, for example, an illustration of the Capgras delusion in which parents believe that their child has been taken away and replaced with another.
This condition is a form of misidentification, with the patient being unable to identify and recognize a particular person, although everyone else the patient is acquainted with can be clearly identified. Capgras delusion appears to be caused by functional changes in the brain, and it is commonly linked with brain injury, dementia, and diseases which damage the brain as a result. It can also be the result of chemical imbalances in the brain which alter perception, making it harder for patients to identify the people they know.
As with many delusions, treatment for Capgras delusion is challenging. The patient firmly believes that someone he or she knows has been replaced by a double, and any attempts to debunk this will be met with resistance. A therapist or loved one who tries to intervene may inadvertently compound the delusion, as the patient may decide that the people denying the presence of the double are also doubles. Especially in people with a history of mental illness, Capgras delusion can become quite complicated.
Treatment is dependent on establishing a strong therapeutic relationship with the patient in which the therapist neither confirms nor denies the delusion. Over the course of psychotherapy sessions, the patient may be led to slowly understand that he or she is suffering from a delusion. Medications may also be used to manage the patient. In severe cases, however, Capgras delusion may not be treatable, as can be seen in cases of dementia where a patient is experiencing progressive brain damage which eventually leads to more widespread misidentification, such as confusing the identities of family members.