Capgras delusion (where a person believes that a family member has been replaced by an identical imposter) is a terrifying disorder for both those who experience it, and those who are misidentified. From a strictly scientific standpoint, however, Capgras delusion is fascinating. Our knowledge of this disorder has evolved significantly since it’s first discovery, and the history of our understanding is interesting in and of itself.
Capgras syndrome (as it is also called) was first described in 1923 by Joseph Capgras, a French psychologist. The first patient was female, and for a while it was believed that only women could suffer from Capgras syndrome, although this is now known to be untrue.[i] For a period of time (during the heyday of Freud’s psychodynamic approach to psychology) it was believed that Capgras delusions were a result of the brain trying to cope with it’s Oedipal urges; patients were supposedly justifying their sexual attraction to their parents by believing they were imposters. This idea is also now widely discredited.[ii]
At the time Susannah Cahalen was writing Brain on Fire, it was believed the areas of the brain responsible for recognizing faces (the prefrontal cortex) and the parts of the brain responsible for registering emotional recognition of those faces (the limbic system) were not communicating correctly. However, there were people with brain damage that would have affected this communication, but didn’t display Capgras delusions. This also didn’t explain why only close members of the family were the subjects of these delusions. Clearly this miscommunication wasn’t the only factor.
Relatively recent research points to dysfunction in the extended face processing system as a possible cause for Capgras. This system, which is comprised of various parts of the brain, is responsible for recognizing familiar objects, places, and people. This would explain why the delusions are only ever about close family members: only those who were close enough to activate this particular system of neurofamiliarity (a word I just invented) would be confused for strangers.[iii]
More research clearly needs to be done on this fascinating topic.
[i] Merrin EL, Silberfarb PM. The Capgras phenomenon. Archives of General Psychiatry. 1976;33:965–968.
[ii] Lambert, K. (2007, December 6). How Capgras Syndrome Works. HowStuffWorks. Retrieved February 14, 2014, from http://science.howstuffworks.com/life/inside-the-mind/human-brain/capgras-syndrome1.htm
[iii] Thiel, C. M., Studte, S., Hildebrandt, H., Huster, R., & Weerda, R. (2013). When a loved one feels unfamiliar: A case study on the neural basis of Capgras delusion. Cortex, 30, 1-11.