Alzheimer’s disease has been considered something that happens from within, generally speaking — but for the first time, researchers have identified cases that were triggered by a specific medical treatment.
The most common type of dementia, Alzheimer’s is caused by a buildup of amyloid proteins in the brain, with risk factors including age, family history, unhealthy lifestyle behaviors and certain medical conditions.
But in a study published in Nature Medicine, researchers from University College London (UCL) linked growth hormone treatments to the development of Alzheimer’s, according to a UCL press release.
The researchers studied patients who received a type of human growth hormone that was extracted from the pituitary glands of deceased people (c-hGH).
The c-hGH has been shown to lead to greater amounts of amyloid-beta protein in the brain, the researchers found.
FILE - Toronto Star reporter Joe Hall's brain scan images taken during his visit to the Toronto Western Hospital's MRI room on July 29, 2015. (Brian B. Bettencourt/Toronto Star via Getty Images)
Of eight people studied who were treated with c-hGH as children, five developed symptoms of dementia and had already been diagnosed with Alzheimer’s or met the criteria of the disease.
All of them were between ages 38 and 55 when they began experiencing symptoms of cognitive decline, the paper indicated. Genetic testing confirmed that the early disease was not inherited.
"We have found that it is possible for amyloid-beta pathology to be transmitted and contribute to the development of Alzheimer’s disease," said first author Dr. Gargi Banerjee, a researcher at the UCL Institute of Prion Diseases, in the press release.
"This transmission occurred following treatment with a now-obsolete form of growth hormone, and involved repeated treatments with contaminated material, often over several years," he went on.
The researchers emphasized that Alzheimer’s disease cannot be transmitted from person-to-person contact.
"There is no suggestion whatsoever that Alzheimer’s disease can be transmitted between individuals during activities of daily life or routine medical care," said the lead author of the research, Professor John Collinge, director of the UCL Institute of Prion Diseases and a consultant neurologist at UCLH, in the release.
"The patients we have described were given a specific and long-discontinued medical treatment that involved injecting patients with material now known to have been contaminated with disease-related proteins," he added.
FILE - Toronto Star reporter Joe Hall's brain scan images taken during his visit to the Toronto Western Hospital's MRI room on July 29, 2015 (Brian B. Bettencourt/Toronto Star via Getty Images)
The type of growth hormone treatment named in the study was suspended in 1985 when it was found to cause Creutzfeldt-Jakob disease (CJD) in some people.
CJD is a degenerative brain disorder that causes dementia and death.
The findings should be used to help prevent any "accidental transmission via other medical or surgical procedures" in the future, Collinge stated.
Fox News Digital reached out to the UCL team requesting additional comment.
FILE - Alzheimer's Disease, Scan, Brain Of A Patient Affected By Alzheimer's Disease, Axial Section, Median Portion Of Dilated Third Ventricle, Symmetrical Dilation Of Intersections, Whereas The Cortical Horns Are Normal In Size. (BSIP/Universal Images Group via Getty Images)
Dr. Rehan Aziz, a geriatric psychiatrist with Jersey Shore University Medical Center, was not involved in the study but recognized that the paper shows potential evidence for a "very rare but transmissible form" of Alzheimer’s disease.
"The study describes just five Alzheimer’s patients out of the more than 1,800 people who were known to have received growth hormone in this way," Aziz noted.
"Remarkably, the patients all developed Alzheimer’s dementia at young ages, though several of them had complicated histories that may have contributed."
The unusually young age at which these patients developed symptoms suggested they did not have the usual form of Alzheimer’s associated with old age, Aziz said.
"The research raises the question of whether beta-amyloid protein can propagate itself, leading to cascading memory loss and worsening Alzheimer’s pathology," he added.
FILE - A aptient lies in a positron emission tomography (PET) scanner during a demonstration at the Austin Hospital in Melbourne, Australia. (Carla Gottgens/Bloomberg via Getty Images)
Christopher Weber, PhD, director of global science initiatives at the Alzheimer’s Association, was also not involved in the UNC research but reiterated that Alzheimer’s is not contagious.
"You can't catch Alzheimer's by taking care of someone with Alzheimer's," he told Fox News Digital. "Alzheimer’s disease is not transmissible through the air, or by touching or being near someone with Alzheimer’s."
In analyzing the study, Weber noted a few limitations.
"Based on the handful of cases they examined, the authors propose the idea of a ‘rare acquired’ Alzheimer’s, a third explanation for the beginnings of the disease along with sporadic Alzheimer’s and genetic Alzheimer’s," he said.
"However, the study population (eight in this paper) is very small, and these are the only known cases in the literature. Thus, this possible third type of Alzheimer’s is a novel idea, but needs replication and confirmation to add credibility."
FILE - A woman, suffering from Alzheimer's desease, looks at an old picture on March 18, 2011 in a retirement house in Angervilliers, eastern France. (SEBASTIEN BOZON/AFP via Getty Images)
The possibility of creating abnormal amyloid buildup isn’t new, Weber noted, as it’s been demonstrated via injections into animals’ brains.
"We also transfer human Alzheimer’s genes into animals to initiate abnormal, Alzheimer’s-like processes in their brains — but these things do not happen in daily life or in routine medical procedures," he said. "They are extraordinary occurrences."
Although the type of transmission of amyloid beta identified in the UNC study is rare, Weber emphasized that "the scientific and clinical communities must understand the possible risks and ensure that all methods of pathogen transmission are eliminated."
One of these methods is the "complete and conscientious sterilization of surgical instruments," Weber said, which is common practice today.
"Bottom line: We shouldn't put amyloid-beta into people’s brains, either accidentally or on purpose," he said. "And appropriate measures should be in place to ensure that doesn’t happen."