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The new study raises new questions about Alzheimer’s disease. (Representative photo)
Alzheimer’s can be transmitted between humans through rare medical accidents, according to research, although experts emphasize that there is no evidence that the disease can be transmitted from human to human through everyday activities or routine care. The new study, published in the journal Nature Medicine, provides the first evidence of Alzheimer’s disease in living people that appears to have been acquired medically from deceased donors and due to the transmission of a toxic protein that causes the condition. Researchers say a handful of people who received human growth hormone from the pituitary glands of the deceased developed early-onset Alzheimer’s, probably because the hormones used were contaminated with proteins that seeded the disease in their brains.
“We are not for a moment suggesting that you can get Alzheimer’s disease. This is not communicable in the sense of a viral or bacterial infection,” said Professor John Collinge, co-author of the study and director of the MRC Prion Unit. , as for The Guardian.
“It’s only when people have been accidentally inoculated, essentially, with human tissue or human tissue extracts that contain these seeds, which fortunately is a very rare and unusual circumstance,” he added.
The team said the findings may have important implications for understanding and treating Alzheimer’s disease. According to the researchers, the study also reinforces the idea that the disease has similarities to prion disease, including the mechanism by which the proteins involved spread through the brain.
In particular, prion diseases are caused by infectious proteins that misfold and spread in the brain. These diseases usually appear spontaneously; However, more rarely they can arise from a genetic mutation or be transmitted through infected brain or nervous tissue.
For the study, researchers reported how between 1959 and 1985, at least 1,848 patients in the United Kingdom received human growth hormone extracted from the pituitary glands of cadavers. This was used for various causes of short stature: when a child or adolescent is well below the average height of her peers. However, this treatment was withdrawn in the 1980s after it was learned that some patients died as a result of hormone samples contaminated with proteins that cause Creutzfeldt-Jakob disease (CJD). CJD is a rare, fatal disease that affects the brain. Of the 80 such cases in the UK, some were also found to have a protein called beta-amyloid in their brains when they died, a hallmark of Alzheimer’s disease.
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The researchers noted that it was unclear whether these patients would have developed Alzheimer’s symptoms, but cited other research that showed that amyloid beta was present in some of the hormone batches and that these triggered Alzheimer’s-like disease if administered. to the mice. They also noted that once the cadaver-derived human growth hormone procedure was replaced with a synthetic growth hormone, it did not carry the risk of transmitting CJD.
“The patients we have described received a specific and long-discontinued medical treatment that involved injecting them with material that is now known to have been contaminated with proteins linked to the disease,” Mr Collinge said.
“However, the recognition of the transmission of beta-amyloid pathology in these rare situations should lead us to review measures to prevent accidental transmission through other medical or surgical procedures, in order to prevent such cases from occurring in the future,” he added.
Experts said medical procedures should be reviewed to ensure rare cases of Alzheimer’s transmission do not occur in the future.
However, Andrew Doig, professor of biochemistry at the University of Manchester, said experts were already very careful about the transmission of brain tissue between people. He also warned that only eight patients participated in the study, some of whom lacked genetic data, while so far there was no direct evidence of different strains of beta-amyloid.