Vishvajyth Ponnambalam
Research conducted in the UK has found that a now obsolete hormone therapy treatment caused Alzheimer’s, a common and (currently) incurable neurodegenerative disease, by transmitting the disease between the brain tissues of patients. How did this happen and what does this mean with regards to our understanding of the pathology of Alzheimer’s?
A team in University College London (UCL) has found that though Alzheimer’s is certainly not infectious in the same sense as a virus and therefore cannot be spread through physical contact, for example, there is the possibility that it can be transmitted to the brain via certain medical procedures.
The team studied five cases, which were linked to injections of cadaver-derived human growth hormone (c-hGH) that came from donors that are diseased. These injections, which were used to treat different causes of short stature around 50 years ago, were contaminated with brain proteins which are present in Alzheimer’s disease aetiology. These c-hGH injections were used to treat around 2,000 people in the UK between the years of 1959 and 1985.
There have been no reported cases of Alzheimer’s acquired from any other clinical procedures
Its use was suspended because clinicians found that some batches were polluted with a different type of infectious protein. This led to a rare and fatal brain condition called Creutzfeldt-Jakob disease (CJD) in some people. Those patients who did not immediately succumb to CJD ended up eventually developing Alzheimer’s disease. The researchers involved in this study suggest that the Alzheimer’s-related amyloid-beta protein might have been spread mistakenly in the brain during medical procedures in the same way as CJD.
But does this mean that Alzheimer’s could be transmitted from one brain and “infect” another healthy brain without any previous underlying conditions leading to Alzheimer’s naturally? Well, not really. The researchers emphasise that these occurrences are highly unusual, and such cases should not be seen now because the hormone therapy in question has been ceased. Additionally, it is worth noting that there have been no reported cases of Alzheimer’s acquired from any other clinical procedures, so this could potentially be a unique mischance.
An individual’s genetics can lead to early onset before the age of 65
Though the unusually young age of the patients who developed symptoms suggests they did not have the usual sporadic Alzheimer’s usually associated with old age, the research rather supports the long-held belief that the amyloid-beta protein is an important factor in triggering the onset of Alzheimer’s disease.
So, what does this study tell us about Alzheimer’s if anything? Alzheimer’s disease is a pathological form of dementia where people suffer from both motor and cognitive deficits. These can include memory impairment and impairment of social functioning, leading to a poorer quality of life, especially in the elderly. In the UK 11% of over 65’s currently suffer from this condition, which leaps to 50% of over 85’s. Alzheimer’s has a life expectancy of 5 – 8 years, depending on the age of diagnosis. Currently, it is unclear what exactly triggers Alzheimer’s disease, where symptoms typically begin to show after the 65-year mark, but an individual’s genetics can lead to early onset before the age of 65 – as was the case for some of the patients whose data was used in the study – giving them a predisposition to the disease.
Researchers have long known that beta amyloid and some other proteins can cause normal native protein to form abnormal structures.
With what certainty can one make a judgement that the growth hormone that was administered to them years ago led to their brain abnormalities?
The team at UCL also injected the amyloid-beta protein from samples of the c-hGH injections into the brains of mice. This induced amyloid plaques characteristic of Alzheimer’s, seemingly corroborating their theory. Mouse studies conducted as part of the research have confirmed that transplanting Alzheimer’s-affected brain tissue can recreate the disease’s pathology in a new brain. This provides robust evidence of amyloid beta involvement and suggests it could even be a strong enough factor to trigger Alzheimer’s on its own. However, that may not be the case in humans, and further investigations are definitely needed to explore this idea in more detail.
The wider scientific community has approached this study with both interest and scepticism. Donna Wilcock, a neuroscientist at the Indiana University School of Medicine emphasizes the complex medical history of the patients whose data was used in the study. With what certainty can one make a judgement that the growth hormone that was administered to them years ago led to their brain abnormalities?
Moving forwards, the UCL team aim to understand whether these case studies of patients are outliers among those who got the now-obsolete growth hormone therapy, and whether any additional signs regarding the onset of Alzheimer’s disease can be found.
This study illustrates the many medical disasters that have occurred in the past due to negligence, lack of knowledge or both. It serves as a reminder of the lives and quality of living that can be compromised if medical and clinical procedures are not carried out properly. Furthermore, this study highlights the urgency of finding suitable treatments and even a cure for a disease which is only going to rise as the world population ages.
Vishvajyth Ponnambalam
Featured image courtesy of Robina Weermeijer via Unsplash. Image license found here. No changes were made to this image.
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