Five people with Alzheimer’s disease developed the condition as a result of a medical procedure decades earlier, a new study reports. While the procedure that has been implicated is no longer in use, the findings could provide important insights into how the disease progresses, and represent the first evidence of Alzheimer’s being transmitted to living people in this way.
Eight cases of patients in the UK who were treated with human growth hormone derived from cadavers (c-hGH) were reviewed by a team from University College London (UCL) and University College London Hospitals NHS Foundation Trust (UCLH). This practice was used between 1959 and 1985, and at least 1,848 patients are known to have received c-hGH – usually during childhood – to treat various causes of short stature. The cadaver-derived product was withdrawn globally after there were some reports of recipients being infected with prions, and ultimately dying of
In these cases, though, the disease resulted from a medical procedure, which is termed “iatrogenic” transmission.
Once the risk of iatrogenic CJD became clear in the mid-1980s, all use of c-hGH in medical procedures was stopped, and the National Prion Clinic at UCLH has continued to monitor numerous affected patients.
Through post-mortem analysis, it began to emerge that there could be something else going on in the brains of those who died of CJD. There was evidence of
This latest study focuses on eight individuals who did not develop CJD after their c-hGH treatment. Five of them started displaying symptoms consistent with Alzheimer’s-related dementia between the ages of 38 and 55, which progressed and became more severe over time. Of the remaining three, one had no symptoms at all, one had some minor cognitive symptoms, and one met the criteria for a diagnosis of
Since the patients with Alzheimer’s were so
That only left one logical conclusion for the team: that amyloid-beta proteins were
Previous research with animal models provides a precedent for this theory, which the team has been developing since as far back as
But, and this is very important to stress, all this does not mean that Alzheimer’s is contagious.
“The transmission probably requires direct contact with the brain or the presence of circulating pathogenic forms of the proteins in the bloodstream,” professor of neuropathology
This was echoed by Professor John Collinge, the lead author of the new study and director of the UCL Institute of Prion Diseases, in a
What it does mean is that we have more evidence than ever that Alzheimer’s could progress in a similar way to CJD, at least in some cases.
While true iatrogenic cases of Alzheimer’s are likely to be very rare, the team does say that it is important we take a fresh look at medical procedures that could come with a heightened risk of transmission. Primarily, though, in light of the
The study is published in