Guide
In the past, you would have thought it ridiculous if someone told you that Alzheimer's disease could be transmitted from person to person, but now, many studies are showing that this neurodegenerative disease can also be transmitted.
The key factor in the spread of Alzheimer's disease lies in growth hormone.
The latest Nature Medicine paper shows: In the past, a major source of growth hormone was usually extracted from the pituitary gland of a deceased person, and while these growth hormones helped teenagers grow taller, they also brought new "pollution".
Zhou Chen | Writing
01
New research: Alzheimer's disease is 'contagious'
Alzheimer's disease, also known as Alzheimer's disease, is a common neurodegenerative disease. Generally speaking, we usually look for the cause in the family gene, nerve damage. And the latest research shows that Alzheimer's disease can be transmitted from person to person.
The researchers' focus was on individuals who had been treated with growth hormone. Growth hormone is a protein hormone secreted by the pituitary gland, and in the past, a common source of growth hormone was gland tissue extracted from the pituitary gland of a deceased person.
These growth hormones are used for medical purposes and play a key role in promoting the development of bones and muscles. As a result, many parents of children and adolescents may receive growth hormone therapy with cadaveric pituitary gland extract in order to grow taller for their children.
Recently, a number of studies have made this source of growth hormone controversial, that is, people who have received growth hormone injections, especially those extracted from the pituitary gland of deceased people, may develop Alzheimer's disease.
In January 2024, the University College London (UCL) MRC Prion Unit and the John Collinge team at the University College London Institute for Prion Diseases published a study in Nature Medicine that individuals who have received cadaver-derived pituitary growth hormone injections, particularly those treated in childhood, may develop Alzheimer's disease (AD) in adulthood.
The study found that pathological features of Alzheimer's disease, including amyloid-β (Aβ) deposition and neurofibrillary tangles, were present in the brains of these patients, suggesting that iatrogenic Aβ transmission may occur in these individuals, increasing the risk of developing Alzheimer's disease.
While this type of iatrogenic Alzheimer's disease may be rare, the study is a wake-up call for contemporary medical treatment: to prevent accidental transmission through other medical and surgical procedures. "We want to take precautions to reduce the occurrence of those rare cases," Collinger said.
02
Why is Alzheimer's disease contagious?
Why does growth hormone extracted from the pituitary gland of a cadaver trigger the butterfly effect and even be associated with Alzheimer's?
The crux of the problem may lie in the long incubation period of prion infection. Back in 2015, Sebastian Brandner's team at the Institute of Neurology at University College London conducted a study on patients who had been treated with growth hormone extracted from the human pituitary gland and developed iatrogenic Creutzfeldt-Jakob disease (iCJD) as a result.
Creutzfeldt-Jakob disease is a rare neurodegenerative disease that is a type of prion disease, usually caused by a clump of abnormal proteins (prion proteins) that affect the central nervous system, including the brain. Iatrogenic Creutzfeldt-Jakob disease is unique in that it is caused by accidental exposure to prions during medical or surgical procedures.
In this study, the researchers performed autopsies on eight patients aged 36-51 who died of iatrogenic Creutzfeldt-Jakob disease, and strikingly found that four of them showed moderate to severe gray matter and vascular amyloid β (Aβ) pathology, which is typical of Alzheimer's disease.
It is worth mentioning that these patients do not have a pathogenic mutation associated with early-onset Alzheimer's disease or a high-risk gene such as APOEε4, which means that the possibility of Alzheimer's disease due to a family gene can almost be ruled out.
This suggests that transmission of Aβ may be associated with the development of iatrogenic Alzheimer's disease in patients with iatrogenic Creutzfeldt-Jakob disease.
In 2018, Collinger and Brandner's team collaborated on another study in patients who had been treated with growth hormone extracted from the human pituitary gland and developed iatrogenic Creutzfeldt-Jakob disease as a result.
The researchers found that in these patients, relatively young people exhibited significant Aβ deposition, similar to the Aβ deposition produced by experimental animals after transplantation of Alzheimer's brain tissue. Analysis of archived growth hormone vials was then conducted to reveal that certain growth hormone batches associated with patients with Aβ abnormalities contained Aβ protein and other abnormal proteins. This finding implies the possibility of transmission of Aβ.
03
The problem of contamination in clinical trials cannot be ignored
In fact, there is no need to worry, because since 1985, many countries have stopped using cadaveric-derived growth hormone due to health and ethical concerns. Synthetic growth hormones are now more commonly used, and the production and quality of these hormones are generally controlled more precisely.
However, even so, the above research still has its specific value, that is, it calls for attention to iatrogenic prion diseases in clinical medicine, and to avoid infectious diseases such as contact with infected tissues or contaminated medical devices.
On January 7, 2022, the University of Maryland School of Medicine successfully transplanted the heart of a gene-edited pig into a patient, but the patient died unexpectedly two months after the operation. After analysis, the researchers concluded that one of the important reasons was the gradual increase in the cfDNA of PCMV/PRV (PCMV, porcine cytomegalovirus; PRV, porcine roseola virus) in patients after xenotransplantation.
Therefore, these studies are not only an establishment of the relationship between growth hormone and Alzheimer's disease, but also an appeal for medical safety and infection.
Resources
1.Evidence for human transmission of amyloid-β pathology and cerebral amyloid angiopathy. Nature.
2.Transmission of amyloid-β protein pathology from cadaveric pituitary growth hormone. Nature.
3.Autopsies reveal signs of Alzheimer’s in growth-hormone patients. Nature.
4.Signs of ‘transmissible’ Alzheimer’s seen in people who received growth hormone. Nature.
5.Iatrogenic Alzheimer’s disease in recipients of cadaveric pituitary-derived growth hormone. Nature Medicine.
6. Died 60 days later, the cause of the world's first pig heart transplant failure was found.