In a groundbreaking revelation, scientists have unveiled the first documented evidence of Alzheimer’s disease potentially being transmitted among living individuals. Published in Nature Medicine, the findings illuminate a unique case where Alzheimer’s appears to have been transmitted through a contaminated medical treatment, raising intriguing questions and highlighting the need for further research.
Unveiling a Medical Enigma
For years, Alzheimer’s disease has been understood as primarily a sporadic condition of late adult life or a hereditary ailment caused by specific gene mutations. This recent study, however, sheds light on an entirely different scenario, suggesting a rare instance of transmission through medical intervention.
The Link to Cadaver-Derived Growth Hormone
The individuals examined in the study had all received treatment with cadaver-derived human growth hormone (c-hGH) during their childhood. This hormone, extracted from the pituitary glands of deceased individuals, was used to address various growth concerns. Notably, c-hGH was administered to around 1,848 individuals in the UK between 1959 and 1985.
A Contaminated Past
Unfortunately, c-hGH use ceased in 1985 after it was discovered that certain batches were contaminated with prions, infectious proteins responsible for Creutzfeldt-Jakob disease (CJD). As a result, safer synthetic growth hormone replaced c-hGH in medical practice.
Connecting the Dots – Prior Research
Previous research by the same scientists revealed a worrying link between c-hGH treatment and the early accumulation of amyloid-beta protein deposits in the brains of patients diagnosed with iatrogenic CJD. Additionally, a 2018 study showed that archived c-hGH samples harbored amyloid-beta protein and could transmit its pathology to lab mice.
Building Upon Past Findings
These findings led the researchers to hypothesize that individuals exposed to contaminated c-hGH who didn’t develop CJD might later develop Alzheimer’s disease.
The Alarming Cases
The latest study delves into eight cases of individuals who received c-hGH treatment as children, often for several years. Five of these individuals developed dementia symptoms, either receiving an Alzheimer’s diagnosis or meeting diagnostic criteria. Notably, neurological symptoms emerged at a surprisingly young age, ranging from 38 to 55 years old.
Confirming the Suspicion
Biomarker analyses provided further support for Alzheimer’s diagnoses in two patients and suggested the disease in another. An autopsy confirmed Alzheimer’s pathology in another individual. The uncommonly early onset of symptoms strongly suggests this deviated from typical late-onset sporadic Alzheimer’s.
Genetics and Safety Measures
Genetic testing ruled out inherited forms of Alzheimer’s in the affected individuals. Since c-hGH treatment is no longer used, the risk of new transmissions through this route is eliminated. However, the researchers emphasize the importance of reviewing safety measures to prevent inadvertent amyloid-beta transmission through other medical or surgical procedures previously linked to CJD transmission.