Now here’s a real oddity. Imagine waking up in the hospital from an accident and seeing people you don’t know sitting around your bed. The thing is these people are actually people you know. You think they are imposters. It isn’t your mother sitting next to you; it’s an imposter pretending to be your mother. This strange problem is called the Capgras Syndrome or delusion. It was named after the person who discovered it, the French psychiatrist Jean Marie Joseph Capgras.

So, what causes this problem? There is a small area in the Brain called the Fusiform Gyrus that is responsible for us recognizing people’s faces. When a trauma such as a stroke effects this part of the brain, we can no longer recognize faces. Can you imagine what that would be like? Weird, huh. Once we recognize someone, the fusiform gyrus sends a signal to a structure called the amygdala which registers the emotional significance of the person you just saw. So, when you see your wife or girlfriend (or son, daughter, etc.) you experience feelings of happiness. Well, in the case of the Capgras delusion the fusiform gyrus is intact but the pathway to the amygdala is not working correctly. The result is that you when you see someone you should recognize you believe they are an imposter posing as someone else.

The interesting thing with this problem is that it only happens you see someone. If your mother calls you on the phone you would have no problem knowing it was her. Since the auditory pathways are not effected by the brain trauma, you do not experience the delusion. This shows that the Capgras delusion is specific to visual processing.

So, what is the prognosis for someone who has Capgras syndrome? The damage to the pathway from the fusiform gyrus to the amygdala is unfortunately irreversible. Treatment usually involves therapy where the person is taught to establish empathy with other people and how not to validate their delusions. Antipsychotics have also been used with variable results. Capgras Syndrome is yet another example of how we need a normal functioning brain to experience even simple everyday things.