by Five patients in the UK have developed Alzheimer’s disease that appears to be the result of contaminated injections they received as children decades ago, according to a new study that could change the way scientists think about the causes of dementia – and cause anxiety in patients who underwent the same therapy.
All five patients received injections of human growth hormone from cadavers for several years as a treatment for very short stature, according to the study, published Monday in the journal Nature Medicine. The scientists extracted the hormone from the cadavers’ pituitary glands, which are located at the base of the brain.
What the scientists did not realize at the time, however, was that in some cases another substance was also removed, contaminating the batches: amyloid-beta protein. This protein is involved in the formation of the characteristic brain plaques seen in Alzheimer’s. Researchers said that they can not fully explain how exposure to these proteins could cause the creation of plaque and tangles in the brain that causes Alzheimer’s disease.
Alzheimer’s cases are generally divided into two main groups: cases caused by genetic mutations and those that develop sporadically in the population in people over 65 due to several risk factors, such as smoking, obesity and high blood pressure.
The patients in the new study did not fall into those two groups. They developed symptoms of dementia between the ages of 38 and 55. None had genetic mutations associated with early-onset dementia, the study found.
The authors of the study said that their results suggest that there could be a third way that Alzheimer’s could develop: through contaminated medical products.
Several doctors who regularly treat children for hormone-related issues and were not involved in the research said they were surprised by the findings.
“This is new information that is unknown to the medical community,” said Dr. Kupper Wintergerst, who chairs the endocrinology section of the American Academy of Pediatrics.
Other doctors said they were concerned that a therapy once considered safe had caused so much harm.
“To hear that Alzheimer’s is linked to a medical treatment, that’s disturbing,” said Dr. Dennis Chia, associate clinical professor of pediatric endocrinology at the David Geffen School of Medicine at UCLA.
Christopher Weber, director of global scientific initiatives at the Alzheimer’s Association, noted that the study was very small. The results would be more credible if other scientists found similar results in future studies.
Weber said there is no danger to the general public.
“Alzheimer’s disease is not contagious,” said Weber, who was not involved in the new study. “You can’t catch Alzheimer’s by taking care of someone with Alzheimer’s. Alzheimer’s disease cannot be transmitted through the air, or by touching or being close to someone with Alzheimer’s.”
Still, he said the study’s findings weren’t entirely new.
“We have known for a long time that it is possible to create an abnormal amyloid buildup – similar to that seen in Alzheimer’s – in the brain of the animal by injecting it with amyloid-beta,” said Weber. “We also transfer human Alzheimer’s genes into animals to induce abnormal Alzheimer’s-like processes in their brains.”
Cadaver-derived growth hormone was given to 27,000 children worldwide from 1959 to 1985, according to the new study, including about 7,700 patients in the United States. Doctors used hormones taken from cadavers before a synthetic version was available.
It is possible that other patients who received cadaver-derived hormones are at a higher risk of Alzheimer’s, the authors of the study said. But they said they don’t expect to see a huge wave of cases.
“The actual risk of transmitting Alzheimer’s disease in this context is actually very low and these are likely to be very rare cases,” lead study author Dr. John Collinge, neurologist and director of University College London’s Prion Disease Institute, said at a news briefing on Thursday.
Collinge said patients should be aware of their potential risk for Alzheimer’s and, if necessary, seek testing and treatment.
“It may be that if we catch people at an early stage” of Alzheimer’s, he said, “they may be more amenable to available treatments.”
Children being treated for short stature today are not at risk, as doctors have been using synthetic growth hormones since 1985.
“I don’t think people should be scared,” said Dr. Paul Kaplowitz, professor emeritus at National Children’s Hospital who specialized in pediatric growth disorders.
Kaplowitz noted that in 1977, US manufacturers developed a safer way to purify cadaver-derived human growth hormone, which significantly reduced the risk of contamination. Patients treated in the US with cadaver-derived growth hormone after 1977 are likely to have a very low risk.
“You’d think if this was a big problem, we’d have a lot of cases by now,” said Kaplowitz, who was not involved in the new study.
Other dangerous proteins
Although earlier research by Collinge and his team suggested that patients who received cadaver-derived growth hormone might be at risk for Alzheimer’s, they began following the patients because of concerns about a different disease: Creutzfeldt-Jakob disease, or CJD. a rare and fatal condition. which also resulted from contaminated hormone samples.
CJD is a cousin of bovine spongiform encephalopathy, commonly known as mad cow disease. More than 250 growth hormone patients have been diagnosed with CJD worldwide.
Doctors believe patients developed CJD because of hormone samples contaminated with prions – little-understood proteins that can cause normal brain proteins to fold into abnormal shapes. Thirty-five patients treated with cadaveric human growth hormone in the US have died of CJD.
For many years, people who lived in the UK or traveled to the UK or other places affected by mad cow disease were banned from donating blood, for fear of passing the disease on. The Food and Drug Administration lifted that ban in 2022.
Collinge said he does not know whether the proteins that appear to cause Alzheimer’s can be transmitted through blood transfusions or organ donations. A spokesman for the American Society of Transplantation said that its scientists know of no links between organ transplants and an increased risk of Alzheimer’s.
“It’s an interesting question,” Collinge said at the briefing. “It’s not something we looked at.”
Scientists have had evidence for some time that CJD can be transmitted through blood transfusions, and the American Red Cross prohibits people who have received growth hormone from donating blood.
But a spokesman for the American Red Cross said in a statement that “there is no scientific evidence” that donated blood could lead to the accumulation of amyloid protein in the body or increase the risk of Alzheimer’s. The Red Cross is in close contact with the FDA and other international health agencies that oversee blood safety to ensure that its recommendations include the latest science, said spokesman Daniel Parra.
The new study raises questions about how Alzheimer’s begins. Alzheimer’s may have more in common with CJD than previously suspected, Collinge said.
“This could have important implications for the future understanding and treatment of Alzheimer’s disease,” he said in a statement. Although there have been no other reported cases of Alzheimer’s acquired through other medical care, the study “should enable us to review measures to prevent accidental transmission through other medical or surgical procedures to prevent such cases in the future.”
For more information, patients treated with cadaver-derived human growth hormone in the US can call the National Institute of Diabetes and Digestive and Kidney Diseases at 1-800-860-8747 or email healthinfo@niddk.nih. gov.
Patients being treated in the UK can email the National Prion Clinic at uclh.prion.help@nhs.net.
This article was originally published on NBCNews.com
