Imposter disorder explains how man's wife was 'stolen'
点击量： 时间：2018-01-09 02:01:01
By Helen Thomson (Image: Thomas Hoepker/Magnum Photos) A MAN with the delusional belief that an impostor has taken his wife’s place is helping shed light on how we recognise loved ones. Capgras syndrome is a rare condition in which a person insists that a person they are close to – most commonly a spouse – has been replaced by an impostor. Sometimes they even believe that a much-loved pet has also been replaced by a lookalike. Anecdotal evidence suggests that people with Capgras only misidentify the people that they are closest to. Chris Fiacconi at Western University in London, Ontario, Canada, and his team wanted to explore this. They performed recognition tests and brain scans on two male volunteers with dementia – one who had Capgras, and one who didn’t – and compared the results with those of 10 healthy men of a similar age. For months, the man with Capgras believed that his wife had been replaced by an impostor and was resistant to any counterargument, often asking his son why he was so convinced that the woman was his mother. First the team tested whether or not the volunteers could recognise celebrities they would have been familiar with throughout their lifetime, such as Marilyn Monroe. Volunteers were presented with celebrities’ names, voices or pictures, and asked if they recognised them and, if so, how much information they could recall about that person. The man with Capgras was more likely to misidentify the celebrities by face or voice compared with the volunteer without Capgras, or the 10 healthy men. None of the volunteers had problems identifying celebrities by name (Frontiers in Human Neuroscience, doi.org/wrw). It is thought that we recognise people based on signals generated in two interconnecting brain pathways. One pathway is responsible for the structural content of the face – “yes, I recognise that nose, those eyes and that hair”. The other carries information about the emotional connection you have with that person. It’s this pathway that is disturbed in people with Capgras, Fiacconi says. His work suggests that the importance of that emotional signal in recognising someone may rise as the nature of the emotional connection increases. This might explain why it is most often loved ones that are believed to be impostors. This new, small study hints that people with Capgras might have trouble identifying other people too, but that the only ones they think are impostors are those they have the strongest emotional connections with. Fiacconi says that because the emotional connection to a loved one is paramount in recognising them, if it isn’t working properly, the affected person adopts the belief that their loved one cannot be who they appear to be. “For people you are close to, that ’emotional colour’ is much more important than structural features, and so in order to rationalise these two competing sources of info and resolve the mismatch, they adopt the belief that the spouse is an impostor,” says Fiacconi. “Someone with Capgras will say ‘she looks just like my wife, but it can’t be her’ because their emotional colour is disturbed.” People with Capgras have damage to their frontal cortex, a region involved in interpreting feedback from the body which may also be involved in processing emotions. This region is a target for future research. This article appeared in print under the headline “Man’s wife stolen by a syndrome” More on these topics: