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Genetic Linkage

Transmissible Alzheimer’s Disease? Long-Ago Growth Hormone Treatment and a Legacy of Cannibalism and Mad Cows

A stylized slice through an Alzheimer's brain depicts amyloid-beta plaques in brown and tau tangles in blue.

Five people treated for pituitary dwarfism decades ago with human growth hormone (hGH) pooled from cadavers have shown cognitive decline reminiscent of early-onset Alzheimer's disease. Their dementia likely arose from transmission of the bits of amyloid-beta protein that lie behind Alzheimer's delivered along with the needed hormone, initiating a molecular chain reaction that led to brain effects decades later. Recombinant DNA technology has since provided a pure source of the hormone.


The cognition decline in these people is iatrogenic – caused by a medical procedure. The pooled hGH included infectious proteins, called prions (pronounced "pree-ons"), short for "proteinaceous infectious agent." The research appears in Nature Medicine from long-time prion researcher John Collinge, director of the University College London Institute of Prion Diseases, and colleagues.


The team followed 8 patients. Two of the five with clinical signs of Alzheimer's died during the investigation, and autopsy revealed the telltale brain changes. Two other patients had mild cognitive impairment, and the eighth had no symptoms. None had mutations that cause Alzheimer's disease, ruling out genetics as a cause.


To continue reading, go to DNA Science, where this post first appeared.




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