Medical Miscue May Have Given Patients Alzheimer's

Doctors once sought to make very short children taller by injecting them with growth hormone taken from the brains of dead people. The procedure was banned 40 years ago—and cadaver-derived pituitary growth hormone (c-hGH) replaced with a synthetic version—when scientists discovered patients had also received bits of protein known as prions that triggered the rare and incurable Creutzfeldt-Jakob disease. In 2015, researchers discovered a protein considered a hallmark of Alzheimer's disease was transmitted, too. Now, they say that amyloid-beta protein has triggered Alzheimer's in patients as young as 38. As Stat News reports, "they are the first known cases of transmitted Alzheimer's disease, likely a scientific anomaly."

This doesn't mean Alzheimer's is contagious. But the authors of a study published Monday in Nature Medicine, who treated five patients who were among 27,000 worldwide to receive c-hGH as children between 1959 and 1985 and then went on to develop Alzheimer's, "provide tantalizing evidence that, under extraordinary circumstances, Alzheimer's disease is transmissible by a prion-like mechanism," neuroscientists Mathias Jucker and Lary C. Walker write in a commentary. This means Alzheimer's is not only caused by aging and factors related to genetics, environment, and lifestyle, but can also be iatrogenic, or medically acquired.

While the finding is new, "we've known for a long time that it is possible to create abnormal amyloid buildup—similar to that seen in Alzheimer's—in the brain of an animal by injecting it with amyloid-beta," Christopher Weber, director of global science initiatives at the Alzheimer's Association, tells NBC News. The five patients described received the amyloid-beta proteins involved in the formation of brain plaques decades before the protein "propagated into disease-causing plaques," per Stat. Scientists aren't entirely sure how Alzheimer's developed but expect only a small number of patients who received c-hGH to suffer as a result. (The study describes one patient who was asymptomatic.) They do, however, stress the need to properly sterilize neurosurgical instruments to avoid prion transfer, per Stat. (More Alzheimer's disease stories.)