Seeds of dementia can be passed on in surgery

The seeds of Alzheimer’s disease can be transmitted during medical procedures, scientists have said, leading to calls for the monitoring of blood transfusions from the elderly and people with a family history of dementia.

Researchers at University College London discovered that patients who had developed Creutzfeldt-Jakob disease (CJD) after treatment with human growth hormone also showed signs of Alzheimer’s in their brains after death. The hormone contained misfolded amyloid beta proteins, capable of setting off the deadly chain reaction that can lead to dementia.

Professor John Collinge, of the Medical Research Council’s Prion Unit and UCL Institute of Prion Diseases, said: ‘‘We have now provided experimental evidence to support our hypothesis that amyloid beta pathology can be transmitted to people from contaminated materials.

‘‘We cannot yet confirm whether medical or surgical procedures have ever caused Alzheimer’s disease itself.’’

From 1958, about 30,000 children with growth deficiency were treated with growth hormones from dead bodies. However, in 1985, three patients were found to have developed CJD and the practice was banned. When post-mortem examinations were carried out in 2015 on seven of the patients who had died of CJD, their brains were found to contain large amounts of amyloid beta protein, a sticky deposit that affects brain cells in patients with Alzheimer’s. Although none had developed dementia, scientists said it was likely they would have done, had they lived longer.

The research, in the journal Nature, shows for the first time that the seeds of Alzheimer’s were passed along accidentally with CJD. Experts said it emphasised the importance of never again injecting material from the human central nervous system into patients during medical procedures. Alzheimer’s groups said it was highly unlikely that the disease would be passed on during a medical procedure.

Dr David Reynolds, chief scientific officer at Alzheimer’s Research UK, said: ‘‘Although the findings might sound concerning, strict guidelines surrounding the sterilisation and use of surgical equipment have already been introduced since the discovery of prion protein contamination and CJD.’’

– Telegraph Group