Researchers from University College London (UCL) have identified a potential link between a now-discontinued medical treatment and the development of Alzheimer's disease.
The study, published in Nature Medicine, suggests that a specific type of human growth hormone used between 1959 and 1985 may have played a role in the onset of Alzheimer's in a small number of cases.
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The treatment in question, cadaver-derived human growth hormone (c-hGH), was administered to at least 1,848 individuals in the United Kingdom during the specified period to address various causes of short stature.
The researchers ruled out inherited Alzheimer's disease in the five patients for whom genetic testing samples were available. The findings suggest a potential transmission of amyloid-beta pathology, a protein associated with Alzheimer's disease, due to the contaminated c-hGH treatment.
"We have found that it is possible for amyloid-beta pathology to be transmitted and contribute to the development of Alzheimer's disease," First author Dr Gargi Banerjee from UCL Institute of Prion Diseases said. "This transmission occurred following treatment with a now obsolete form of growth hormone, and involved repeated treatments with contaminated material, often over several years."
The growth hormone was extracted from pituitary glands of deceased individuals and was utilized until its withdrawal in 1985. The withdrawal occurred after the recognition that some c-hGH batches were contaminated with prions, infectious proteins responsible for causing Creutzfeldt-Jakob disease (CJD), a rare and fatal brain condition.
The recent study conducted by the UCL researchers investigated eight individuals who had been treated with c-hGH during childhood, often over several years. Five of these individuals exhibited symptoms of dementia, and either had a confirmed diagnosis of Alzheimer's or met the diagnostic criteria for the condition.
Another individual met criteria for mild cognitive impairment. Notably, these patients developed neurological symptoms between the ages of 38 and 55, indicating an unusually young onset compared to the typical sporadic Alzheimer's associated with old age.
Implications for Future Research
While the research suggests a potential link between c-hGH treatment and Alzheimer's disease in these cases, researchers caution that these circumstances are highly unusual.
There have been no reported cases of Alzheimer's acquired through other medical or surgical procedures, and the risk of new transmission via c-hGH treatment is nonexistent since it is no longer used.
The study's findings have prompted researchers to advocate for a review of measures to prevent accidental transmission of amyloid-beta through various medical or surgical procedures.
However, Lead author Professor John Collinge, Director of the UCL Institute of Prion Diseases, emphasized that there is no indication that Alzheimer's can be transmitted between individuals during daily life or routine medical care.
Co-author Professor Jonathan Schott, Chief Medical Officer at Alzheimer's Research UK, noted that while the circumstances leading to Alzheimer's in these individuals are rare, the findings could offer valuable insights into disease mechanisms.
Further research is needed to enhance understanding and treatment of Alzheimer's disease, particularly its potential similarities with other neurological conditions such as CJD.
The paper underscores the importance of continuous research and vigilance in medical practices to ensure the prevention of inadvertent transmissions of disease-related proteins.
