Imagine reliving the day of a dental appointment every day, endlessly. Doctors say one amnesia patient in Northern England is doing just that.
Every morning, the 38-year-old man he wakes up thinking it is the day of the dental appointment in 2005 when his rare form of amnesia began. According to a case study published in the journal Neurocase, "Each morning he is surprised to wake up in his mother's house [where he now lives]. He wakes up believing that he should still be in the military, stationed abroad. Every day he thinks it is the day of the dental appointment" -- an experience reminiscent of the movie "Groundhog Day."
"One of our reasons for writing up this individual's case was that we had never seen anything like this before in our assessment clinics," lead researcher Dr. Gerald Burgess, lecturer in Clinical Psychology at the University of Leicester, said in a statement. "We do not know what to make of it."
The strange story began in March 2005, when the man went to the dentist's office for root canal surgery and had an injection of local anesthetic. After the hour-long procedure he was pale, slow and minimally responsive. "A vasovagal incident was suspected," the study says, referring to the vagus nerve and a possible disruption in its role regulating heart rate and blood pressure.
The man was taken to the hospital where he remained for several weeks, unable to remember anything for longer than 10 minute intervals. Eventually, those periods of memory expanded to 90 minutes, where they have been stuck ever since.
After several tests that indicated the otherwise healthy man did not have brain damage, but did have psychological disfunction, doctors ruled out some common forms of amnesia and diagnosed him with a rare form of "anterograde" amnesia, meaning the inability to form new memories. They do not believe the condition was caused by the anesthetic.
Anterograde amnesia is usually accompanied by brain damage, which this man did not have. They say the onset of the condition included "complete and profound forgetting" after the first night's sleep following the dental surgery. This form of the condition may need its own new category.
No other cases exactly like it have been documented, the researchers say, but the study cites four other cases that they think may have factors in common.
Though the man still understands his identity and has maintained his intelligence, he has to use an electronic diary to remind him about important parts of his life and tasks he has to manage. He remembers his family members, "though he expects everyone to still be the age they were in March 2005," the study says. "If asked, he may say, 'I know I have a memory problem,' or 'I think it is March 2005, but it is not.'"
The man has only been able to make one lasting new memory in the past decade, the realization of his father's death. His doctors suggest the personal and emotional significance of the loss of his father could have affected his brain in different ways and triggered a permanent emotional tie to the memory that can last beyond the 90 minute limit.
The researchers suspect the man's amnesia is possibly the result of a breakdown in his brain's ability to process molecules, specifically, a failure of mRNA protein synthesis, which is usually involved in memory consolidation and making permanent memories.
They say much more study is needed to understand this rare and disturbing case and figure out why such memory disruptions happen. "I don't think that at this point the dental anaesthetic or root canal can be blamed," said Burgess. "I feel the story lies elsewhere, but that the preceding incident needed to be documented and not ignored."