Jess Franklin

Let’s imagine Patient X: a 36-year-old man who has been seriously injured in a car accident. When he awoke from a coma, all seemed fine until he noticed his mother standing by his bedside. “Who is this woman? She looks exactly like my mother, but she's an imposter! Get her out of here!” he exclaimed. Every time she visited, he would say she was a fake double, and despite her pleading with him, sharing old family stories and personal details only she could know, Patient X refused to believe otherwise. After months at home, he began to complain his pet poodle had also been replaced by an identical replica and even doubted whether his own house was not actually a duplicate. His mother was particularly traumatised by this, describing her son as living “in a parallel universe”.

Patient X is most likely suffering from Capgras Syndrome – a rare delusional disorder whereby patients believe that certain family members, friends, pets, or even their own home are ‘imposters’. The delusion may begin with the person closest to them, and then gradually extend to other members of the family, with patients eventually believing the whole family are imposters. Those suffering from Capgras Syndrome can even see themselves as a double, and doubt their own identity when they catch their reflection in the mirror. One patient was reported to be so disturbed when they saw their own ’doppelgänger’ that they threw all of the mirrors in the house away. Another patient was said to fly into a jealous rage every time she saw her own reflection, as she believed it was “the other woman” trying to steal her husband.

The disorder can occur as a result of degenerative diseases such as Alzheimer’s, in conjunction with other mental conditions such as schizophrenia, or after traumatic brain injury (where patients may have no other cognitive problems and an otherwise clean bill of mental health). 

As with most neurological conditions, the precise cause is not known. The most prominent theory revolves around the ‘fusiform face area’, a region of the brain which identifies a face and tells us that we recognise it. This message is normally sent to the amygdala (another brain region), which tells us the emotions we associate with the recognised face. In Capgras Syndrome, it is suggested that the connection between visual recognition and emotional recognition is broken. Therefore, although patients recognise a face, they do not experience any of the feelings they would normally associate with that face – there is no sense of familiarity. The brain then tries to work out a compromise and explain the situation, its conclusion being that the recognised person was somehow replaced by an impostor.

Sadly, very little is known about how to treat Capgras Syndrome. Those who experience it alongside other mental disorders may be helped by medication; those who experience it due to physical brain trauma may eventually re-establish the connection and be able to associate faces with emotion. However, many patients – despite constant reasoning and persuasion – may remain adamant a loved one is an imposter forever.