“The person’s primary delusion is that a close relative or friend has been replaced by an impostor, an exact double, despite recognition of familiarity in appearance and behavior. The patient may also see himself as his own double. For persons suffering from Capgras Syndrome they typically believe they exist in a world of impersonators. This feeling in a delusional world of doubles can be so alarming that it drives the Capgras sufferer to psychotic behavior. The syndrome typically has the following characteristics:

• The person is convinced that one or several persons known by the sufferer have been replaced by a double, an identical looking impostor.
• The patient sees true and double persons.
• It can may extend to animals and objects.
• The person is conscious of the abnormality of these perceptions. There is no hallucination.
• The double is usually a key figure for the person at the time of onset of symptoms. If married, always the husband or wife accordingly.”