For the first time, a team of researchers at University College London has reported clear evidence that Alzheimer's disease spreads from person to person. A team of researchers reported that at least five cases of Alzheimer's were believed to have arisen as a result of decades-old medical practices. Researchers have demonstrated how human growth hormone** transplants toxic proteins into children and causes early-onset Alzheimer's disease through some unusually rare case studies.
For about 25 years, starting in the late 50s of the 20th century, human growth hormone was used sporadically in children with certain physical development problems. This hormone is called"c-hgh"(human growth hormone extracted from cadavers), which was extracted from the pituitary gland of the deceased person, was then injected into children who were abnormally short in stature.
Over the years, an unexpectedly high percentage of children receiving growth hormone** have developed a deadly neurodegenerative disease, Creutzfeldt-Jakob disease. This disease is caused by toxic misfolded proteins called prions. By 1985, there was conclusive evidence that growth hormone was associated with Creutzfeldt-Jakob disease. Researchers have found that some growth hormone samples contain toxic prions, which sows the seeds of neurodegenerative diseases in healthy brains. Growth hormone that originated in humans was quickly replaced by safer synthetic hormones.
Recently, a team of researchers found strange signs of Alzheimer's disease while studying brain tissue samples from growth hormone patients who died from Creutzfeldt-Jakob disease. These deceased patients had abnormally high levels of amyloid deposition, which is a telltale sign of Alzheimer's disease. So, the question arises: Can Alzheimer's spread from person to person like other prion diseases?
Because these patients die of Creutzfeldt-Jakob disease in such a short period of time, there is no way to tell if they will develop Alzheimer's. However, a subsequent study did find that some C-HGH samples contained an accumulation of amyloid, and animal studies showed that mice injected with contaminated growth hormone showed pathological signs of Alzheimer's disease.
So, at this point, the hypothesis that Alzheimer's disease spreads from person to person is credible, but researchers still need some kind of hard evidence. To do this, the team looked at eight patients with neurological disorders who were recently referred to the National Prion Clinic in London. All eight patients received C-HGH in childhood ** and are now between the ages of 38 and 55.
Five of these patients were diagnosed with early-onset dementia but had no pathological signs of Creutzfeldt-Jakob disease. All five patients met the diagnostic criteria for Alzheimer's, but importantly, they did not show a genetic predisposition to early-onset dementia.
In their latest published study, the researchers wrote:"Here, we describe recipients who experienced dementia and biomarker changes within the AD (Alzheimer's disease) phenotypic spectrum, suggesting that AD, like CJD (Creutzfeldt-Jakob disease), has environmentally acquired (congenital) forms as well as late-onset sporadic and early-onset inherited forms"The researchers wrote. "While congenital AD may be rare, and there is no indication that a [amyloid-] can be transmitted from person to person during activities of daily living, the recognition of it underscores the need to revisit measures to prevent accidental transmission through other medical and surgical procedures"。
Andrew Doig of the University of Manchester said the new findings were comprehensive and careful, but cautioned against making broader extrapolations from essentially just eight very rare cases.
Doig said"While the new Alzheimer's reported here is of great scientific interest because it sheds light on a new way the disease is spreading, there is no reason to be afraid of it, as the way the disease is caused was stopped more than 40 years ago. The transmission of diseases between human brains in this way will never happen again"。
Susan Kohlhaas of the Alzheimer's Research Centre in the UK agrees, arguing that the findings do prove an unusually rare instance of Alzheimer's spreading from person to person, but also points out that such cases are unlikely today. Instead, Kohlhaas said, the discovery is expected to provide researchers with new insights into how the disease develops, helping them find new ways.
Kohlhas said"There is no evidence that amyloid can be transmitted through any other route, such as daily activities or routine medical procedures. But this study sheds more light on how amyloid fragments spread within the brain, providing further clues as to how Alzheimer's develops and potential new targets for the future. "
The new study was published in the journal Nature Medicine.