Banned Medical Treatment May Have Transmitted Alzheimer's Proteins

Researchers found evidence that five individuals medically acquired Alzheimer's disease long after receiving a cadaver-derived growth hormone treatment.

In a new study published on January 29 in Nature Medicine, scientists uncovered evidence that Alzheimer's disease could be transmitted from human to human through medical procedures.

The findings do not indicate that Alzheimer's is contagious. However, it does suggest that amyloid beta proteins, if introduced into the brain through medical treatment or procedures, could potentially "seed" and lead to the onset of the disease.

Promising treatment had significant flaws

According to the study, between 1959 and 1985, a medical treatment involving growth hormones derived from the pituitary gland of a cadaver was used to treat various medical conditions, including growth hormone deficiency in children. Officials banned it in 1985 after some people who received the treatment experienced Creutzfeldt-Jakob disease (CJD) — a fatal brain condition caused by misfolded proteins called prions.

It turned out that some cadaver-derived growth hormone batches used in the treatment were contaminated with these prions.

Moreover, some of the people who died of Creutzfeldt-Jakob disease also had amyloid beta proteins in their brains. This protein is associated with the development of Alzheimer's disease. Further investigation found that some cadaver-derived treatment lots were contaminated with these proteins.

What the study found

Researchers examined eight people in the United Kingdom who received this discontinued treatment in childhood but did not experience CJD. Of the eight individuals, five showed symptoms of early-onset Alzheimer's disease, and two had milder symptoms of cognitive impairment. One individual did not show signs of dementia. However, among those with early-onset disease, symptoms presented differently than what's typical for Alzheimer's.

Moreover, only one of the five individuals with Alzheimer's or Alzheimer's-like symptoms had a genetic risk factor for the disease.

The researchers suggest that the amyloid protein-contaminated hormone treatments "seeded" the protein in the individuals' brains, causing the damage.

The scientists stress that these findings in no way suggest that Alzheimer's can be transmitted through close contact or routine medical care.

However, in a press release, lead researcher Professor John Collinge, a neurologist and Director of the University College London Institute of Prion Diseases, said, "The recognition of transmission of amyloid-beta pathology in these rare situations should lead us to review measures to prevent accidental transmission via other medical or surgical procedures, in order to prevent such cases occurring in [the] future."

Additionally, this discovery underscores the potential similarities between prion-induced diseases and Alzheimer's.

"Importantly," Collinge said, "our findings also suggest that Alzheimer's and some other neurological conditions share similar disease processes to CJD, and this may have important implications for understanding and treating Alzheimer's disease in the future."