Five people who developed Alzheimer's disease appear to have acquired it through a medical treatment they received decades earlier as children, according to research published in Nature Medicine by a team at UCL and University College London Hospitals. All five had been given human growth hormone extracted from the pituitary glands of deceased donors, known as cadaver-derived human growth hormone. That treatment was withdrawn in the 1980s after it was found to transmit Creutzfeldt-Jakob disease.
The researchers found that batches of the hormone could carry fragments of amyloid, the protein that accumulates in the brains of people with Alzheimer's. The five individuals went on to develop symptoms of the disease, confirmed through diagnostic testing. The team also worked to exclude other explanations, checking for genetic variants associated with young-onset Alzheimer's and considering whether growth hormone deficiency itself might raise Alzheimer's risk.
The route of transmission described here is narrow and no longer possible. As Dr Gargi Banerjee, an Alzheimer's Research UK Clinical Research Fellow on the study team, pointed out, the cases followed repeated exposure to contaminated material from a form of growth hormone that is now obsolete, often over a period of years. Nothing in the findings suggests Alzheimer's spreads between people in everyday life or through routine care.
What the cases do offer is a rare natural experiment in how amyloid behaves in the human brain. If seeding amyloid can eventually produce Alzheimer's symptoms in people who had no genetic predisposition, that strengthens the case for amyloid's role early in the disease process - and gives researchers a clearer target as they work on treatments and prevention.