It comes after scientists studied medical records of four people who had brain bleeds caused by a build up of amyloid, a hallmark of the incurable disease.
All had neurosurgery two or three decades earlier as children or teenagers, raising the possibility deposits may be transferred in a similar way to those who caught Mad Cow Disease from human growth hormones contaminated with infectious rogue proteins known as prions.
Although amyloid is known as being a key indicator of Alzheimer’s, researchers did not find evidence of the disease in this study.
However, the study by experts at University College, London, study has raised alarm.
Professor Sebastian Brandner said: “We have found new evidence that amyloid beta pathology may be transmissible.
“This does not mean that Alzheimer’s can be transmitted, as we did not find any significant amount of pathological tau protein which is the other hallmark protein of Alzheimer’s disease.
“Our findings relate to neurosurgical procedures done a long time ago.
“Nevertheless, the possibility of pathological protein transmission, while rare, should factor into reviews of sterilisation and safety practices for surgical procedures.”
Researchers looked in the pathology archive at the National Hospital for Neurology and Neurosurgery for biopsy and autopsy materials of young adult patients with confirmed amyloid beta pathology, which can lead to brain bleeds or harmful plaques, in the brain’s blood vessels. These deposits occur increasingly frequently in older individuals but only very rarely in younger people.
Four cases were identified – three of them were in their 30s and one was aged 57 – all of whom had experienced brain bleeds caused by amyloid deposits in brain blood vessels.
None had any known genetic causes that predispose to this pathology in younger people.
A separate review of the medical literature supported the discovery by identifying four other case studies with similar pathology and past surgical history.
As these patients were all men with a history of head trauma, research teams had previously speculated that those were correlated.
The new study suggests otherwise, as all patients had a history of childhood neurosurgery, three were women and only one had a history of head trauma.
In a comparison group of 50 people of similar ages from the same archives, the researchers did not find any amyloid beta pathology and only three had a recorded history of childhood neurosurgery.
Previous work in laboratory animals has shown that tiny amounts of abnormal amyloid beta protein can stick to steel wires and transmit pathology into the animals’ brains, but this paper is the first to suggest the same may be possible in humans.
This study provides evidence for an association between neurosurgery in childhood and the development in late adult life of cerebral amyloid angiopathy, a rare condition in which amyloid is deposited in the walls of blood vessels in the brain and leads to a higher risk of haemorrhage.
Dr David Reynolds, of Alzheimer’s Research UK, said: “While it is too early to draw any firm conclusions from such a small study, the finding that people with a rare amyloid-related disease all had brain operations early in life raises the possibility of amyloid having been passed from one person to another during neurosurgery.”
In a statement The Royal College of Surgeons and the Society of British Neurological Surgeons said: “Any study that investigates potential links between contaminated neurosurgical instruments and the transmission of disease is to be welcomed, as the more we understand about eliminating risk, the greater the benefit for patients.”
The research is published in Acta Neuropathologica.