What Reduplicative Paramensia Says About the Nature of Delusions

At the very end of his life, Henry James lost his sense of place. The renowned author of novels such as Portrait of a Lady and The Golden Bowl, James was also celebrated for his travelogues and evocative portraits of Europe. But after suffering a pair of strokes at his flat in London, he began to insist he was somewhere else: California, or Cork, Ireland, or at his mansion on the South coast of England. At times, he seemed to believe he was in several places at once: “This place I find myself is the strangest mixture of Edinburgh and Dublin and New York and some other place that I don’t know,” he wrote. In what later came to be known as his Napoleonic fragments, James also dictated to his secretary two letters that suggest he believed he was the former French emperor himself. He died not long after these events.

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Neurologists suspect that James had a condition known as reduplicative paramnesia, in which one believes a person, place, or object exists in duplicate, identical to the original, only displaced. The condition is extremely rare—fewer than 50 cases have been documented in the research literature. The first case was described in 1903, by neurologist Arnold Pick. Though it is well understood that reduplicative paramnesia tends to follow brain injury to the right hemisphere and frontal lobes, scientists are still piecing together exactly how it arises and what it might tell us about how delusions work.

Reduplicative paramnesia is one of a handful of so-called delusional misidentification syndromes, in which patients develop false beliefs about doubles and duplicates. The best known of these are Capgras and Fregoli, where people believe certain familiar individuals, such as husbands and wives, have been doubled or take on the appearance of someone else. But there are numerous variations. Some people suffer from reduplication of time, where they become convinced that they exist in two distinct but parallel time points. Others develop autoscopy: They believe their body is the double of another body. Those with something called intermetamorphosis are certain that they have switched identities with another person or animal, or that other people or objects have physically and psychologically transformed into other beings. All of these conditions are thought to be caused by a disturbed sense of familiarity.

Dysregulated feelings of familiarity can lead to a sense that one’s wife is not actually one’s wife.

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Not long ago, English researcher Huw Green encountered a patient in the rehab ward of the Addenbrooke’s Hospital, a major trauma center where he works in Cambridge, England. The 42-year-old woman was admitted to the hospital after having been kicked in the face by a horse. When she emerged from an 11-week case of amnesia, she began to insist that she was at a different Addenbrooke’s in her hometown, some distance away. She was convinced that she had recently been treated there or that she needed to get there to see her therapist. She rated her certainty that this other Addebrooke’s existed at a 10 out of 10, even though she was well aware that her doctors and her partner strongly disagreed with her. It was a classic case of reduplicative paramensia. She could still draw a relatively accurate map of the United Kingdom, so her geographical knowledge was otherwise intact. She also briefly became convinced that she had more children than she did and that her partner had a double, though these delusions faded after two weeks.

Many very specific kinds of delusions, hyper-narrow sets of perceptions and beliefs, have been described in the research literature. “It must tell us something about the parameters that are available to vary our perceptual experience, about the basic kinds of things that our brain is doing, the basic functions that it’s performing,” says Green. “And if you interfere with those, then you can get certain kinds of odd beliefs.” This is the predictive processing account of delusions, according to which the brain is just a machine for making inferences, and any unusual perceptual input will inevitably lead to such unusual beliefs. Feelings of affective deadness or lack of vitality or depression can sometimes be connected with people ultimately believing that they are dead or that everyone else is dead. Dysregulated feelings of familiarity can lead to a sense that one’s wife is not actually one’s wife.

A separate theory of delusions called the “two-factor” account posits that unusual perceptual input is not enough. An additional cognitive glitch must prevent the person from accurately updating or evaluating their beliefs. The two-factor theorists point out that certain kinds of neurological conditions cause unusual perceptual experiences but don’t lead to delusions. But the predictive processing camp argues that we don’t have any evidence of this secondary factor or know what it is. “Nobody can test it, so you can’t isolate it,” says Green. “You can’t confirm its presence or absence.” The debate between the two sides is quite heated and at a kind of impasse, he says.

What was interesting about the woman who had been kicked by the horse was that she was able to correct some of her false beliefs, just not the one about a double of the hospital existing somewhere else. For example, the beliefs about extra children and versions of her partner went away. In addition, she initially suffered substantial memory loss for events that had taken place during the two years prior to her injury. Most significantly, she forgot that her father had died of cancer 15 months before the accident. When she was reminded of this fact, she was able to come to terms with it, and to understand that he was gone, fairly quickly. This fact, that she did not seem to have a more universal problem with correcting false beliefs, made Green and his colleagues think her case provides special evidence for the predictive processing account of delusions.

Belief updating, in any case, is poorly understood. “There isn’t really an agreed upon mechanism for what the brain does when it finally forms a belief and says, ‘Okay, this checks out. I’m gonna sign off on this belief,’” says Green. “For a while there was some interest in the idea that perhaps people with delusions are prone to disinhibition, where they jump to conclusions more readily: the-jump-to-conclusions bias. The idea was that these people require fewer bits of information before they’re prepared to draw a conclusion.” But then that idea fizzled because a number of large-scale, rigorous meta-analyses suggested that while it is common in schizophrenia, it’s not specifically associated with delusions. “It lost its explanatory force,” he says.

For Green, the Addenbrooke’s case was also a reminder of how easy it is for delusions to arise. “One thing reduplicative paramnesia might tell us is that you don’t need to change that much in a person’s experience or in their brain to give rise to really colorful, flamboyant beliefs,” he says. When his patient went home from the hospital, the problem resolved itself. Her sense of familiarity was restored and so she was restored to herself.