A real-life case of Groundhog Day has been reported by psychologists at the University of Leicester, with a man waking up thinking it is the same day every day following a root-canal treatment at the dentist.
The 38-year-old man suffered from memory loss following the treatment and for the last 10 years has only been able to remember up to 90 minutes at a time.
Every day he wakes up he thinks it is the same day he went to the dentist, leaving researchers completely baffled. The case is reported in the journal Neurocase.
Gerald Burgess, of the University of Leicester, said: "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, and we do not know what to make of it, but felt an honest reporting of the facts as we assessed them was warranted, that perhaps there will be other cases, or people who know more than we do about what might have caused the patient's amnesia."
Currently the case is believed to be unique, so Burgess is hoping other people who suffered similar symptoms or health professionals that have treated it will come forward.
"Our experience was that none of our colleagues in neurology, psychiatry, and clinical neuropsychology could explain this case, or had seen anything like it themselves before," he said.
After the man, from the UK, went to the dentist for a routine procedure under local anaesthetic, he lost the ability to form new memories. His personality did not change and he is fully aware of his identity – he has managed to get by with the aid of an electronic diary and prompts.
Burgess has since studied hundreds of cases and there is no explanation: "Amongst our allied health professions, what we did know about from decades of research and hundreds of case studies, is that bilateral damage to the hippocampal and/or diencephalon structures causes profound amnesia, and in the absence of apparent structural damage to these structures, it left an explanation widely open to speculation."
He said they believe profound amnesia does not only occur through visible damage to these structures – that these just appear to be required for holding or retaining information before they are processed through other circuits for permanent storing.
"An acquired or manifest deficiency of protein synthesis, required for permanent restructuring of synapses in the brain, seemed an intriguing speculation, and one we hope there might be further human research into," Burgess said.
"This speculation was sparked by two seemingly key coincidences of one, timing when this protein synthesis stage occurs coincides with the patient's forgetting at 90 minutes or thereabouts, and two, both 'episodic' and 'procedural' memories appear to require successful protein synthesis to occur for long-term memory permanence, and the patient cannot retain any new either episodic or procedural memories - and this is unusual compared to traditional cases of amnesia.
He said the anaesthetic or root canal cannot be blamed as there is no sufficient evidence to support this: "I feel the story lies elsewhere," he said. "There is nothing more than that to go on now. ... I would be most grateful if others have stories or theories of this or some kind to come forward."