Alzheimer’s: Disease has already been transmitted between humans – 01/29/2024 – Balance and Health

Scientists have shed new light on how Alzheimer’s spreads through the brain and found the first evidence of human-to-human transmission through a human growth hormone, the use of which is currently banned.

The study, published in Nature Medicine on Monday (29), examined a small group of people who were among at least 1,848 patients treated between 1959 and 1985 with a growth hormone extracted from cadavers.

Some of the overall group had already died from the brain disorder Creutzfeldt-Jakob disease (CJD) because their hormone infusions contained infectious proteins called prions that cause severe abnormalities in the brain.

The results indicate parallels between the evolution of Alzheimer’s and CJD, potentially boosting research into diagnostics and therapies to combat all forms of dementia.

The study examined eight people who received the hormone as children but did not develop CJD. The scientists found that five of these patients showed symptoms consistent with early-onset Alzheimer’s.

In three of the patients, biological studies and autopsies supported a diagnosis of Alzheimer’s, and were suggestive in a fourth.

“Our findings suggest that Alzheimer’s and some other neurological conditions share similar disease processes to CJD,” said John Collinge, lead author of the research and professor at University College London.

“This could have important implications for understanding and treating Alzheimer’s disease in the future,” he added.

The WHO (World Health Organization) estimates that dementia affects more than 55 million people worldwide.

The researchers emphasized that they found no evidence that Alzheimer’s is transmissible in daily life or common medical care.

The findings suggested that the patients’ growth hormone treatment had been contaminated with proteins of a type known as beta-amyloid, researchers say.

These proteins, which stick together and form harmful plaques in brain cells, are increasingly considered a major cause of Alzheimer’s.

The research sample size was small, but the scientists said their outline of a new mechanism for the onset of Alzheimer’s would inform the quest to develop diagnostics and treatments for the disease.

A study published last week claimed that a commercially available blood test had shown high levels of accuracy in early detection of tau, another type of protein implicated in causing Alzheimer’s.

“There is evidence that beta-amyloid aggregates can travel across synapses in the brain, spreading dementia,” said Andrew Doig, professor of biochemistry at the University of Manchester, who was not involved in the Nature Medicine paper. “This work supports that idea.”

The researchers behind the paper said it would be important to review medical safeguards to ensure there was no risk of accidental contamination of patients with beta-amyloid proteins through procedures previously implicated in the transmission of CJD.

Human growth hormone treatment was banned after it was linked to CJD, and synthetic substitutes are now used.

“There is no evidence to suggest that [o Alzheimer] can be transmitted through any other route, such as everyday activities or routine medical procedures,” said Susan Kohlhaas, executive director of research and partnerships at the charity Alzheimer’s Research UK.

“But this study has revealed more about how amyloid fragments can spread within the brain, providing more clues about how Alzheimer’s disease progresses and potential new targets for future treatments,” he added.