It seems that in very rare circumstances, Alzheimer’s disease can be transmitted between people. January 29 researchers in the journal Nature Medicine They reported that five people who had received contaminated growth hormone as children developed Alzheimer’s unusually earlier than usual. “This study shows for the first time that Alzheimer’s disease is iatrogenic,” said neurologist John Culling of the Institute of Prion Diseases at University College London.
Researchers emphasize that Alzheimer’s disease is not contagious through routines of daily life such as caregiving and most medical environments. “We’re not saying you can get Alzheimer’s from other people,” Kalinge said. This disease cannot be transmitted in the form of viral or bacterial infections.
Carlo Condello, a neurobiologist at the University of California who was not involved in the study, agrees. He says: “We do not believe that sporadic Alzheimer’s disease is a contagious disease. “It only occurs under very artificial and outdated medical conditions, and it does not occur in today’s conditions.”
Alzheimer’s disease is not transmitted through daily life routines and most medical environments
to report Science NewsMost cases of Alzheimer’s occur sporadically in the elderly (for example, in the United States, 1 in 9 people age 65 and older have Alzheimer’s).
Symptoms of five people with Alzheimer’s started early (between the ages of 38 and 55), and the researchers ruled out mutations known to cause early forms of Alzheimer’s in three of the patients for whom genetic information was available.
All subjects had received growth hormone injections during childhood or adolescence. These hormones, used to treat various developmental disorders, were extracted from the pituitary gland of cadavers and combined (this procedure is no longer done). Later, it was found that some of these compounds are infected with prions, i.e. infectious and abnormal proteins, and cause the disease called Creutzfeldt-Jakob. Worldwide, more than 200 people got this disease. This type of growth hormone treatment was discontinued in 1985, and doctors now use synthetic versions of growth hormone.
It seems that the combination of growth hormones that were used before had another problem. In their previous study, Kalinge and colleagues found higher-than-expected levels of beta-amyloid in the brains of four people who had died of Creutzfeldt-Jakob. Accumulation of this adhesive protein is a characteristic of Alzheimer’s and in this case it was a warning signal that some of these proteins may have been transferred to recipients along with prions.
In 2018, researchers reported that beta-amyloid found in some hormone compounds can be released into the brains of mice, suggesting that this protein acts in some ways like infectious prions.
The researchers now report eight more people who received contaminated growth hormone and were referred to their clinical team. None of the subjects had Creutzfeldt-Jakob disease, but three had previously been diagnosed with Alzheimer’s. Further investigations showed that two other people also have Alzheimer’s and two people also showed symptoms of cognitive impairment. One person had no symptoms.
According to the researchers’ conclusion, the most probable cause of these Alzheimer’s cases is receiving beta amyloid through contaminated growth hormone in early life. Candello calls this interpretation plausible and says: “What was in those extracts could have had such an effect.”
Scientists cannot definitively say that contaminated growth hormone caused Alzheimer’s disease in these people. For example, childhood problems that required growth hormone therapy or other medical procedures such as radiation therapy may contribute to early-onset Alzheimer’s or cognitive problems. A number of people had seizures, which may affect cognitive problems or brain pathology. According to Kundello, we may never get a definitive answer.
Beyond the rare conditions described, the results of the present study may provide clues about how Alzheimer’s disease can infiltrate the brain.
