Deposits of beta-amyloid proteins in the brain can be transmitted by soiled neurosurgical instruments, a new study suggests.
In recent years, different searches testify to a possible human-to-human transmission of beta-amyloid protein deposits in the brains of animals and humans and, ultimately, to a possible transmissibility of dementia and Alzheimer’s disease. This is not the only hypothesis: inflammation or neurodegeneration are other serious pathogenic avenues of Alzheimer’s disease, but more and more indications of a disease similar to prion disease accumulate.
Deposits of this beta-amyloid protein tend to spread gradually in the brain, suggesting a slow virus cause. On the other hand, studies objectify images in certain brains which could make think of diseases with slow virus, the prions.
A new transmission study
In a new study, published in Acta Neuropathologica, researchers at the UCL Institute of Neurology studied the medical records of four people who had brain hemorrhages caused by the buildup of beta-amyloid in the blood vessels of the brain (cerebral amyloid angiopathy).
They found that the four people had had brain surgery two or three decades earlier, in childhood, raising the possibility that beta-amyloid deposits could be transmitted by soiled neurosurgical instruments (“amyloid seeds”), similar to the slow viruses involved in prion dementias such as Creutzfeldt-Jakob disease.
Alzheimer’s and beta-amyloid protein
Beta-amyloid protein is best known to be one of the proteins that cause deposits in the brain affected by Alzheimer’s disease (along with tau proteins), but researchers have found no evidence of Alzheimer’s disease. ‘Alzheimer’s in this population of still young patients.
“It is well known that the abnormal proteins seen in Creutzfeldt-Jakob disease have been transmitted between patients by certain medical and surgical procedures and we investigated whether this could be the case for beta-amyloid protein,” said Professor Sebastian Brandner of the UCL Institute of Neurology, London.
A review of medical records
Researchers examined the archives of the National Hospital of Neurology and Neurosurgery for biopsies and autopsies of young adult patients with known beta-amyloid disease, which could lead to brain hemorrhages or plaque deposits in the vessels. blood from the brain. These amyloid protein deposits are occurring more and more frequently in older people, but very rarely in younger people.
Four cases were identified – three of them were in their thirties and one was 57 years old – all had brain hemorrhages caused by amyloid deposits in the blood vessels of the brain. None had known genetic causes that predispose to this pathology in young people.
Consistency with the literature
A parallel review of the medical literature confirmed the finding by identifying four additional case studies with similar pathology and previous neurosurgical procedures. Since these patients were all men with a history of head trauma, research teams had previously speculated that the disorders correlated with trauma.
The new study suggests otherwise, since all of the patients had a history of childhood neurosurgery, three were female, and only one had a history of head trauma. In a comparison group of 50 people of similar ages from the same records, researchers found no beta-amyloid brain pathology and only three had a history of childhood neurosurgery.
The transmissibility of beta-amyloid protein
Previous work in laboratory animals had shown that small amounts of the abnormal beta-amyloid protein could be passed from animal brain to animal brain, but this study is the first to suggest that this may actually be possible in the man.
“We found new evidence that brain beta-amyloid angiopathy may be transmissible. This does not mean that Alzheimer’s disease can be transmitted, however, because we have not found any significant amount of the pathological tau protein which is the other characteristic protein of Alzheimer’s disease, ”notes Brandner.
An analysis to be broadened
“Our findings relate to neurosurgical procedures performed a long time ago, but the possibility of pathological transmission of proteins, while rare, should be considered in sterilization and safety practices for surgical procedures.”
“Neurosurgery is more and more common in the elderly, and as beta-amyloid pathology increases with age, it increases the risk of transmitting beta-amyloid protein to other people in the same hospital,” explains Dr Zane Jaunmuktane, from the same UCL Institute of Neurology.
As this study is small and retrospective, the authors hope their findings will prompt other teams to pursue this research further. They are currently trying to expand their analysis to more archives across the UK.
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