In a breakthrough experiment described TODAY in the journal Nature, researchers in London suggest that some patients may have acquired the Alzheimer’s protein, amyloid, from a medical treatment.
From 1958 to 1985, 30,000 people worldwide were exposed to a contagious, highly fatal brain disorder called Creutzfeldt-Jakob disease (CJD). A particular protein — called a prion — that was unknowingly present in human growth hormone treatments, caused these infections.
John Collinge, a neurologist at University College London, and his colleagues studied the brains of eight adults, aged between 36 and 51, who had all died of CJD after receiving contaminated hormone injections as children. But autopsies on their brains also revealed that seven of them harbored the amyloid protein associated with the early stages of Alzheimer’s disease. It is unheard of for people in this age group to have such proteins.
“What we found, very much to our surprise, was that of the eight patients, four had quite significant, some severe, deposition of amyloid protein, the Alzheimer’s protein,” Collinge said in a teleconference discussing the results. These patients had damage to the blood vessels in their brain typical of Alzheimer’s. Only one patient, he said, did not have any signs of amyloid.
This study does not suggest that Alzheimer’s disease is contagious or a threat to the blood supply, but the findings do raise a longstanding question of whether amyloid-beta proteins can behave like prions. If they do, the protein could pose a contamination risk to hospitals, given Alzheimer’s patients and their biological samples are not treated with the same biohazard protocols as those with prion disease.
While the authors stress that this does not mean Alzheimer’s is contagious in the everyday sense, there are implications for surgical transmission even when instruments are sterilized. Amyloid proteins may, like prions, be resistant to conventional sterilization techniques.
For now, the findings only apply to those who may have received injections of growth hormone prior to 1985, before the treatment switched to entirely synthetic sources. But it raises the need for a host of new studies that may help us better understand Alzheimer’s, and other degenerative brain diseases, and some of the more unexpected ways they might develop.