by Alzheimer’s disease has been passed on to patients who are given hormones extracted from corpses, scientists have shown for the first time.
Five people are believed to have developed Alzheimer’s after they were inadvertently treated with human growth hormone containing the seeds of dementia.
The thyroid hormone was given to more than 1,800 short children in the UK between 1959 and 1995 before it was withdrawn when it was shown to cause Creutzfeldt-Jakob disease (CJD).
Now, scientists at University College London (UCL) have discovered that the same batch responsible for CJD cases appears to have triggered Alzheimer’s in some patients. The youngest developed symptoms of dementia at just 38 years of age.
Professor John Collinge, director of UCL’s Prion Disease Institute and consultant neurologist at UCLH, lead author of the research, said: “We are not suggesting for a minute that you can catch Alzheimer’s disease. You cannot get it by being a carer or living with a husband or wife who has the disease.
“The patients we described were given a specific long-term medical treatment, which involved injecting patients with material now known to be contaminated with disease-related proteins.
“However, identifying transmission in these rare cases should lead us to review measures to prevent accidental transmission through other medical or surgical procedures, to prevent such cases in the future.”
Amyloid-beta proteins found in hormones
British scientists first made the discovery while studying the brains of eight people who died of CJD after being injected with human growth hormone.
Unexpectedly, four of the patients had massive levels of amyloid beta protein – a sticky deposit that forms among brain cells and prevents them from communicating properly with each other in Alzheimer’s patients.
Although none of them developed dementia, scientists say they probably would have, had they lived longer.
Researchers then looked for the original growth hormone stored at the Department of Health, and discovered that it contained the misfolded amyloid-beta proteins associated with Alzheimer’s.
When they injected the banned hormone into the brains of the mice, the animals began to develop symptoms of neurodegenerative disease.
Now, scientists have discovered that five people who have been treated with the hormone have developed the symptoms of Alzheimer’s disease despite being only 38 to 55 years old. None of them had a genetic risk for the condition.
First author Dr Gargi Banerjee (UCD Institute of Prion Diseases) said: “We have found that amyloid-beta pathology can be transmitted and will contribute to the development of Alzheimer’s disease.
“This transmission occurred after treatment with a now obsolete form of growth hormone, and involved repeated treatments with contaminated material, often over several years. There is no indication that Alzheimer’s disease can be acquired from close contact, or during the provision of routine care.”
Amyloid proteins come in different strains
The misfolded amyloid proteins are thought to assemble into “stacks” that grow over time until they become so long that they collapse, forming new “seeds”.
Each seed continues to grow, until this unrestrained accumulation of amyloid in the brain begins to kill brain cells.
Dr Susan Kohlhaas, executive director of research and partnerships at Alzheimer’s Research UK, said: “This study has revealed more about how amyloid fragments can spread within the brain, providing further clues to how Alzheimer’s disease progresses and new targets possible for tomorrow’s treatment. .”
No cases of Alzheimer’s acquired from any other medical or surgical procedures have been reported but experts said it was important to review measures and possibly introduce better decontamination methods for surgical equipment.
The team also found that the amyloid proteins come in different strains, like viruses, and drugs that target the main strain may allow less dominant, untreatable forms to develop.
Co-author Professor Jonathan Schott, honorary consultant neurologist at UCLH, said: “These findings provide potentially valuable insights into disease mechanisms, and pave the way for further research which we hope will improve our understanding of the causes of Alzheimer’s are more typical, later. disease.”
Commenting on the new research, Dr Richard Oakley, associate director of research and innovation at the Alzheimer’s Association, said: “It is not known how common Alzheimer’s transmission was in the 1,800 people who received this treatment and the study only looked at the records of eight people. people.
“Today, patients receive synthetic alternatives that are approved for safety and do not carry the risk of disease transmission.”
The research was published in the journal Nature Medicine.
