By Matthew Cobb
This is a rather sad story, although it does have a happy ending. A paper by Ryan Darby and David Caplan from Harvard Medical School [reference below] describes an unusual case of Capgras syndrome – in this unpleasant condition a patient is convinced that someone close to them, such as a family member or friend, has been replaced by an impostor. This is one of many kinds of delusion known as delusional misidentification syndromes (DMS). (I note in passing the tendency for psychiatry to fall victim to the nominal fallacy – the suggestion that if you give something a name, you have in some way explained it. Our ignorance of the brain and the mind, and even more so of the misfunctioning brain and mind, is profound.)
A variety of psychiatric and neurological disorders can cause Capgras syndrome, but the impostor delusion is virtually always focused on a human. In the case described by Darby and Caplan, a 71 year old man who suffered from a range of conditions (bipolar disorder amongst others) became convinced that his cat had been replaced by an imposter. Hence the tasteless pun in the title of the paper: ‘ “cat-gras” delusion’.
According to Darby and Caplan, the poor man
became obsessed with the idea that his pet cat had been replaced by an imposter cat that was involved in the conspiracy against him. He knew that the current cat resembled his pet cat physically, but that the personality or psychic core of his cat had been replaced.
A series of psychological and physical tests revealed the patient had a number of problems – perhaps caused by repeated head injuries incurred when he was a professional hockey player. Many of these were linked to memory retrieval, and Darby and Caplan suggest that one source of Capgras syndrome may be to do with retrieving recognition memories, and they come up with an elaborate hypothesis to explain the underlying processes that may be involved:
We, therefore, propose a model where the delusional belief content in DMS results from dysfunctional linking between externally perceived objects and appropriately retrieved internal autobiographical memories associated with an object, leading to an erroneous learned belief that a familiar external object is a new, distinct entity (explaining the reduplication of physical bodies by the creation of duplicate, imposter identities), or that an internally generated memory is erroneously linked to an unfamiliar external object (leading to the reduplication of identities by the creation of new, disguised persons.
Strikingly, they do not propose any experiments that could test their theory.
This is not the first reported case of Capgras syndrome focused on a cat – there have been two others, and there have also been reports involving a d*g and two birds. However, the authors claim their study is novel as the patient clearly had neurological defects as well as psychiatric problems.
The good news, however, is that
‘His symptoms improved with medications and he has had no further delusions of imposters replacing his cat.’
JAC: You can read more at Discover Magazine, though Matthew read the original paper.
h/t @neuroskeptic
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Darby, R., & Caplan, D. (2016). “Cat-gras” delusion: a unique misidentification syndrome and a novel explanation Neurocase, 1-. You can find it here ($$$). [JAC: I have a pdf which I’ll provide IF you really need it.]
Interesting. Surprised that CET was not involved as well but who knows.
“Strikingly, they do not propose any experiments that could test their theory.”
Perhaps because psychiatry is not science – not yet anyway.
In his 1998 book Phantoms in the Brain, V.S. Ramachandran (not a psychiatrist, but a clinical and research neurologist) describes many of the deceptively simple and elegant experiments he does with his patients.
Much of chapter 8 of Phantoms in the Brain deals with Capgras’ delusion. One significant empirical observation was that when the patient spoke to his parents by telephone, he (the patient) did not believe that the person on the other end was merely impersonating their parent, but was their true parent. It was only in face-to-face interaction that the delusion was in evidence.
If the authors of the paper referred to in the OP could not think of any way to probe the delusion in the patients they were working with, they probably were not trying hard enough.
That Discover article does not include a picture of the cat. That is TERRIBLE journalism. The original article claims to show “PET and CT findings” but it’s ALL imaging of the dude’s head – again, no cat shown!
I’m shocked – shocked! – at the grim state of publishing today.
I agree. I looked eagerly for a photo of the cat, and the article, even in the original paper, doesn’t have a picture of the damn cat!
Maybe they convinced the patient that the cat was genuine by giving it a PET scan. 🙂
More likely a CAT scan…
That wouldn’t work. He mistook his cat for another cat. A CAT wouldn’t be convincing.
Are there medications for religious delusion? A cocktail of education and no childhood brainwashing.
Extreme paranoia is bad news for us all. But small doses probably allow for some people to be more cautious or skeptical.
Oh, that is very sad. In both directions.
Identifying the cat (per Caitlin), has the potential to identify the patient. Given the complicating diagnoses, this is probably not a good idea, even if one ‘pole’ of the patient gave permission.
‘His symptoms improved with medications and he has had no further delusions of imposters replacing his cat.’
Or is the impostor cat just getting better at the deception? Is it possible that his memory of the real cat has been overlain by his memory of the impostor, such that he would not recognise the real cat if he saw it?
(Better not suggest that to him!)
cr
I’ve a friend whose required dosage of medications varies over the months. EXACTLY that sort of thinking is a mark that “it’s time to adjust your meds, X.” And it’s why I keep the local psychiatric ward’s emergency phone number in my phone.
(Not our “List of X”. I’m sure he has his or her own medication issues.)
For an entertaining yet provocative “treatment” of a delusion, please consider watching LARS AND THE REAL GIRL.
Is it not possible that the cat actually suffered some neurological disease (stroke?) that changed it’s behavior, so that the man in fact was partly right – and the pet had in some sense been replaced, if not physically then mentally?