By Amber Roman
A study published in the prestigious journal Nature Medicine has revealed what could be the first evidence that Alzheimer’s disease could be transmitted from person to person. The findings arose from long-term follow-up of patients who received human growth hormone (hGH) extracted from the brain tissue of deceased donors.
This practice, which took place from 1959 to 1985, involved the use of donated hGH preparations to treat various diseases. However, it came to an abrupt halt in 1985 when it was discovered that around 200 patients worldwide developed Creutzfeldt-Jakob disease (CJD), a rapidly progressive form of dementia linked to prions.
The connection between CJD and Alzheimer’s lies in the nature of prions. These infectious particles, composed of abnormally folded proteins, can be transmitted from one cell to another. While CJD is a rare prion disease, Alzheimer’s, a more common disease, also involves the presence of abnormally folded proteins, amyloid and tau, which could spread in a similar way.
The study examined recipients of donated hGH through 1985, finding that five of them developed early-onset Alzheimer’s disease. Although the authors considered other explanations, they concluded that donated hGH was the likely cause. This discovery suggests that those who received donated hGH before 1985 may have an increased risk of developing Alzheimer’s disease.
Importantly, although hGH is now produced synthetically in laboratories, eliminating the risk of prion transmission, the study raises questions about the safety of past medical practices.
In Australia, where donated pituitary material was used between 1967 and 1985, more than 2,000 people were treated for short stature and infertility. Four cases of CJD were identified, probably related to a contaminated batch. Although the risks of new cases of CJD are considered extremely low, the research underscores the importance of evaluating the long-term consequences of past medical practices.
Early-onset Alzheimer’s, which affects about 5% of cases and is rare before age 50, could have a genetic connection. Despite identifying five cases of Alzheimer’s in people aged 38 to 55, the absolute risk remains low compared to the total number of patients treated worldwide.
The Nature Medicine article emphasizes that Alzheimer’s cannot be contracted through contact or attention to people with the disease. Although the long incubation period of the disease could result in the identification of more similar cases in the future, the researchers emphasize that there is no significant risk to public health.
This pioneering discovery sheds light on the complexity of neurodegenerative diseases and highlights the importance of reviewing and learning from past medical practices to ensure the safety of current and future treatments.
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