A team of researchers at the University College London (UCL) has been studying eight cases of Alzheimer’s linked to injections of human growth hormone that came from the pituitary glands of deceased donors. All the people in the study had been treated as a child with cadaver-derived human growth hormone, or c-hGH, that had been contaminated with brain proteins which are seen in Alzheimer's disease.
The c-hGH was used to treat at least 1,848 people in the UK between 1959 and 1985 for severe short stature. But its use was stopped when experts recognised that some batches were contaminated with a different type of infectious protein, which had caused a rare and fatal brain condition called Creutzfeldt-Jakob disease (CJD) in some people.
‘The new work adds weight to the idea that Alzheimer’s has similarities with prion diseases like CJD, including in the mechanism by which the proteins involved spread across the brain,’ said the team writing in the Nature Medicine journal. They also report that the findings raise the importance of measures, such as ensuring effective decontamination of surgical instruments and precaution while transmitting brain tissue between people.
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However, the researchers stress that there is no evidence the disease can be passed between people through everyday activities or routine care. They also said, ‘there is no ongoing public health risk because the growth hormone treatment is now made synthetically and does not carry the risk of developing CJD.’
‘We’re not suggesting for a moment you can catch Alzheimer’s disease. This is not transmissible in the sense of a viral or bacterial infection,’ said Professor Collinge, co-author of the study and director of the Medical Research Council Prion Unit at UCL.
‘It’s only when people have been accidentally inoculated, essentially, with human tissue or extracts of human tissue containing these seeds, which is thankfully a very rare and unusual circumstance,’ said Professor Collinge.
Moreover, other experts in the field have expressed caution while interpreting the data. ‘The new research into Alzheimer’s reported here is of great scientific interest, but only eight patients were involved in the study, some of whom lacked genetic data,’ said Andrew Doig, professor of biochemistry at the University of Manchester. ‘Further evidence is needed to better understand the different strains of amyloid-beta and its link to disease transmission and onset of Alzheimer's,’ he said.