A finding that could have significant clinical implications suggests a medical procedure transferred a key component of Alzheimer’s disease from one person to another. Published in Nature, the study suggests the seeds of the devastating neurodegenerative disease are transmissible. “It is a new way of thinking about the condition,” notes John Collinge, MD, a neurologist at the University College London in the United Kingdom, who led the research.
In the study, Collinge and colleagues found a disturbing collection of clumps in the brains of eight patients who had died of Creutzfeldt-Jakob disease (CJD), a fatal brain disorder. The majority had sizable aggregates of amyloid-β (Aβ), the key protein implicated in Alzheimer’s disease, in their brain tissue, as well as in the brain’s blood vessels. As children, each of these patients had received human growth hormone isolated from cadavers to treat various growth deficiencies.
“This was unexpected and completely out of proportion for what you would expect to see in this age group,” Collinge reports. The patients were in their 30s and 40s when they died. The researchers could not identify any genetic risk factors for Alzheimer’s in the patients, and they did not expect to see such extensive Aβ pathology in the patients’ brains. The team suspected these individuals developed the pathology because the growth hormone they received for treatment as children was contaminated with seeds of Aβ, as well as the factors that cause CJD.
THE STUDY SUGGESTS THE SEEDS OF THE DEVASTATING NEUROGENERATIVE DISEASE ARE TRANSMISSABLE
The researchers obtained the vials of growth hormone the patients had received as children and analyzed their biochemical contents. The examination revealed the containers had Aβ peptides in them.
Next, the team injected the growth hormone the patients had received into mice that were genetically modified to model Alzheimer’s disease. The researchers compared the development of Aβ plaques in these mice to mice that had received a synthetic form of the hormone. They also assessed the development of the plaques in mice that had been injected with material from patients who died from Alzheimer’s disease.
Injection of the cadaver growth hormone produced the same pathology as the mice injected with the Alzheimer’s tissue. “We saw plaques of the Aβ deposits in the brain tissue … [and] around the blood vessels, just as we had seen before,” Collinge observes. “It reproduced the pathology and formally confirmed there was seeding activity in these vials.”
The results suggest a key component of Alzheimer’s disease is transmissible. But Collinge cautions that transmission in this case occurred as part of particular medical procedures, and that Alzheimer’s is not contagious.
“You can’t catch any of these diseases through intimate contact or care for a loved one with Alzheimer’s disease,” he says. Reassuring as this may be, the prospect of transmission of a neurodegenerative disease by any means is cause for concern — and certainly warrants additional research.
Thomas G. Wilson Jr., DDS
Editor in Chief
From Decisions in Dentistry. March 2019;5(3):6.