February 17th, 2024
By Hyun Cho
A study published in Nature Medicine on January 29 suggests that Alzheimer’s disease can be transmitted between people under very rare and specific conditions. Five people who received contaminated injections of human growth hormone as children developed Alzheimer’s disease unusually early, between the ages of 38 and 55.
However, researchers stress that there is no evidence that Alzheimer’s disease is contagious in everyday life or routine care. Alzheimer’s disease is not transmissible like a viral or bacterial infection, says John Collinge, from the University College London’s Institute of Prion Diseases.
Alzheimer’s disease is a progressive condition that causes memory loss, confusion, and cognitive impairment. It is thought to be caused by the abnormal build-up of proteins called amyloid-beta and tau in the brain. Most cases of Alzheimer’s disease occur in older people, but some rare genetic mutations can cause early-onset forms of the disease.
The five people in the study had received injections of human growth hormone derived from the pituitary glands of cadavers to treat various growth disorders. Some of these products were accidentally infected by prions, which are infectious, misshapen proteins that cause a fatal neurological condition called Creutzfeldt-Jakob disease. The researchers found that the same products also contained amyloid-beta protein, which may have been transferred to the recipients and triggered Alzheimer’s disease.
The researchers did not find any evidence of tau protein tangles in the brains of these individuals, which are another hallmark of Alzheimer’s disease. They also did not find any genetic mutations that could explain the early onset of the disease.
The study raises the possibility that amyloid-beta protein can have a virus-like transmission mechanism, similar to prions. However, this would only occur under very artificial and outdated medical practices, such as the use of cadaver-derived growth hormone, which was discontinued in 1985. Nowadays, synthetic versions of growth hormones are used, which do not pose any risk of transmission.
The researchers caution that their findings do not imply that Alzheimer’s disease can be spread through normal contact or exposure. They also emphasize that more research is needed to confirm their results and to understand the implications for other medical procedures that involve the transfer of human tissues, such as blood transfusions or organ transplants.
Comments