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After a brutal car crash, a 43-year-old Polish man, known only as PA, seemed to “lack a personal sense of identity” and would borrow the identity of whoever happened to be nearby: a hairstylist, an art therapist, and a member of the clergy, to name a few. He didn’t recognize members of his own family, including his own dog; the dog, in turn, didn’t seem to recognize him either. PA’s case report appears in a 2011 edition of the journal Medical Science Monitor.

The Patient: PA was a prominent physician in a provincial area, the head of the ob-gyn department at a hospital in southern Poland. The evening of the car crash, he’d been fighting with his wife, who’d discovered he was having an affair; specifically, they were fighting because his wife was angry that PA intended to take the other woman to a party that night. He ended up taking his wife, after all, but as the couple drove there, he swerved to avoid a head-on collision and crashed into a tree. His wife was not seriously injured, but PA suffered a severe head injury, damaging the front and temporal lobes of his brain.

The Problem: Shortly after the accident, it became clear that PA had lost much of his memory; he didn’t recognize his family, and the woman he’d been cheating with — whom he’d gone so far as to proclaim the “love of [his] life” — was now a stranger to him, too. But more than that, it appeared he’d lost his own sense of self. He tended to “cling to the identities of others,” his physicians write in the case report, by which they mean that he often believed he was whoever he happened to be around at the moment.

A few examples:

“ When a 20-year-old hairdresser was cutting his hair, he took her scissors from her and refused to give them back. He shouted that she could not take away his means of livelihood.”

When a 20-year-old hairdresser was cutting his hair, he took her scissors from her and refused to give them back. He shouted that she could not take away his means of livelihood.” “When PA met Zbyszek, a 29-year-old art therapist, he took the brushes from him and refused to give them back. He shouted that he had to paint a picture in the open because he had to earn a living. He answered to the name Zbyszek and claimed to be 29 years old.”

met Zbyszek, a 29-year-old art therapist, he took the brushes from him and refused to give them back. He shouted that he had to paint a picture in the open because he had to earn a living. He answered to the name Zbyszek and claimed to be 29 years old.” “When the young chaplain of the physiotherapy department … was distributing communion on the ward, PA took his Bible, which had been left for a moment on the table, and refused to give it back. He shouted that they wanted to steal the Bible from him and that he would have nothing to pray from.”

He so clearly was not himself that his own dog didn’t seem to know him, and the feeling was mutual:

T: Is this your dog? [in the presence of his pet, a dachshund, who is barking at him. Apparently, the dog does not exhibit positive feelings towards the patient here and now]. PA: Nothing of the kind! A lump of fur like that! I don’t own a dog. I wouldn’t want such a rubbishy thing! I’m afraid of this dog. It wants to bite me!

The Diagnosis: PA’s symptoms did not fit the typical description of most maladies associated with a traumatic brain injury, and so his doctors made one up for him, calling his condition “borrowed identity syndrome.” (It appears to be the only recorded case of the syndrome; a search in PubMed, which holds more than 20 million journal articles, and a Google search only turn up references to this Polish case.) The case-report authors mention that his particular brain damage is somewhat similar to frontotemporal dementia, a variant of dementia caused by cell degeneration. At the time the journal article was written, PA was 54 years old, and although he seemed to be recalling autobiographical details from his childhood, he had yet to fully recover his sense of self.