A medical procedure involving injections of a discontinued human growth hormone has been linked to the transmission of a protein associated with Alzheimer’s disease in a number of patients, according to a new study published in the journal Nature.
While the study has been hailed “largely theoretical” by the authors, they say further investigation is warranted to determine whether these Alzheimer’s-related proteins could be passed on through other medical procedures.
Study leader Prof. John Collinge, of University College London (UCL) in the UK, and colleagues analyzed the brains of eight recently deceased individuals aged 36-51 who died of Creutzfeldt-Jakob disease (CJD) as a result of treatment with prion-contaminated human growth hormone.
The treatment involved extracting growth hormones from the brains of deceased individuals and injecting them into the brains of individuals with growth problems – most commonly during childhood. However, the therapy was banned in the US in 1985 due to the risk of prion transmission – a protein responsible for CJD.
As well as identifying prion disease in the brains of the eight patients analyzed, Prof. Collinge and colleagues identified high levels of beta-amyloid protein – commonly found in the brains of people with Alzheimer’s disease – in the brains of seven of the patients, while four of these patients demonstrated widespread deposits of the protein.
Beta-amyloid can accumulate in the brain as we age, but the researchers note that it is uncommon to find high levels of the protein in the brains of patients as young as 36-51.
While the team did not identify any signs of tau protein in the brains of these patients – another characteristic of Alzheimer’s disease – they note that if the patients had lived longer, it is possible they could have developed the full neuropathology of Alzheimer’s.
Based on their findings, Prof. Collinge and colleagues believe there is a possibility that beta-amyloid “seeds” could be transmitted accidentally through certain medical procedures, just like CJD prions.
- Alzheimer’s is the most common form of dementia
- Every 67 seconds, someone in the US develops Alzheimer’s
- In the US, Alzheimer’s is the only cause of death in the top 10 that cannot be slowed, prevented or cured.
“Alzheimer’s protein seeds could follow similar transmission pathways,” said Prof. Collinge in a press briefing. “The seeds will potentially stick to metal surfaces whatever the instrument is. The question is whether the instrument will have been exposed to those seeds. With prions, we know quite a lot about that. Certainly, there are potential risks with dentistry where it’s impacting on nervous tissue, for example, root canal treatments.”
However, the team stresses that people should not be concerned about “catching” Alzheimer’s, pointing out that it is not a contagious disease.
“You can’t catch it by living with someone who has Alzheimer’s disease or being a carer,” Prof. Collinge noted. “No one should consider canceling or delaying any kind of surgery. But I think it would be prudent to do some research in this area.”
Dr. Doug Brown, director of research at the Alzheimer’s Society in the UK, notes that while these findings are “interesting and warrant further investigation,” the study is small, observational and there are too many unanswered questions to draw firm conclusions about whether Alzheimer’s can be transmitted via medical procedures.
“There remains absolutely no evidence that Alzheimer’s disease is contagious or can be transmitted from person to person via any current medical or dental procedures.”
Earlier this week, Medical News Today reported on a study by researchers from King’s College London in the UK, in which they revealed the development of a “gene signature” that could be used to predict the development of Alzheimer’s and other age-related diseases.