A small new study raises the possibility that certain markers of neurodegenerative disorders such as Alzheimer’s disease can be transmitted to humans through certain medical procedures.
Researchers conducted autopsies and brain tissue sampling on eight British patients, ages 36-51, who had acquired Creutzfeldt-Jakob disease (CJD), a rare but fatal brain disorder, after undergoing treatment with contaminated human growth hormone derived from cadavers.
Of the eight human brains sampled, researchers found, six exhibited “some degree” of amyloid beta pathology in the grey matter and blood vessel walls. Amyloids are peptides that form the so-called plaques found in the brains of Alzheimer’s patients.
All patients ultimately died of CJD, which is caused by a protein known as a prion. Prion diseases are fatal neurodegenerative diseases caused by misfolded forms of the protein. Although it can be inherited, some cases of Creutzfeldt-Jakob disease are iatrogenic, meaning patients were accidentally exposed to prions in medical treatments or surgery.
For the study, the scientists also looked at 116 patients who also had prion diseases but who did not receive human growth treatment. In those individuals, researchers found no evidence of amyloid beta pathology.
Authors of the study, which was published Wednesday in the medical journal Nature, said although there is no evidence that human prion disease or Alzheimer’s are contagious, the research suggests amyloid beta may “potentially be transmissible via certain medical procedures.”
And although researchers said there were no signs of tau protein -- also characteristic of Alzheimer’s -- the full neuropathology of Alzheimer’s could potentially have developed had the patients lived longer.
In a briefing prior to the study’s release, lead author John Collinge called the presence of amyloid pathology in the relatively young patients a “highly unusual” finding.
Collinge, a professor at the Medical Research Council’s Prion Unit at University College London, said it doesn’t prove that the hormone injections the patients received caused Alzheimer’s, but it raises questions.
He said while no one should delay having surgery, it would be “prudent” to do some more research into the matter.
“The results should prompt investigation of whether other known iatrogenic routes of prion transmission, including surgical instrument use and blood transfusions, could also be relevant to the transmission of (Alzheimer’s disease, cerebral amyloid angiopathy) and other neurodegenerative diseases,” a study statement read.
