Alzheimer’s transmission From donors
Five cases of Alzheimer’s are believed to have arisen as a result of medical treatments decades earlier, suggesting the disease could be transmitted between humans.
The new study provides the first evidence of Alzheimer’s disease in living people that appears to have been medically acquired from deceased donorsandduetotransmission ofatoxicproteinthatcausesthe condition.
According to the University Collegelondon(ucl)anduniversity College London Hospitals (UCLH) researchers, the findings may have important implications for understanding and treating Alzheimer’s disease.
Although the procedure that led to this transmission was stopped in the 1980s, experts recommend medical procedures should be reviewed to ensure rare cases ofalzheimer’stransmissiondo not happen in the future. There is no suggestion the protein (amyloid-beta) can be passed on in day-to-day life or during routine medical or social care.
Alzheimer’s is caused by the build-up of the proteins in the brain, and usually occurs later in adult life with no specific family link, or more rarely it could be an inherited condition that occurs due to a faulty gene. The people described in thestudyhadallbeentreatedas children with a type of human growth hormone taken from dead donors (cadaver-derived human growth hormone or c-hgh). Between 1959 and 1985, this was used to treat at least 1,848 people in the UK and usedforvariouscausesofshort stature – when a child or a teen is well below the average height of their peers.
But the treatment was withdrawnin1985afteritwasrecognised that some c-hgh batches werecontaminatedwithprions (infectiousproteins),whichhad caused Creutzfeldt-jakob disease(cjd)–arareandfatalcondition that affects the brain – in some people.
The lead author of the research, Professor John Collinge, director of the UCL Institute of Prion Diseases and a consultant neurologist at UCLH, said: “There is no suggestion whatsoever that Alzheimer’s disease can be transmitted between individualsduringactivities of daily life or routine medical care. “The patients we have described were given a specific and longdiscontinued medical treatment, which involved injecting patients with material now known to have been contaminatedwithdisease-relatedproteins.
“However, the recognition of transmission of amyloid-beta pathology in these rare situations should lead us to review measures to prevent accidental transmission via other medical orsurgicalprocedures,inorder topreventsuchcasesoccurring in future.
“Importantly, our findings also suggest that Alzheimer’s and some other neurological conditionssharesimilardisease processes to CJD, and this may have important implications for understanding and treating Alzheimer’s disease.”
The researchers previously reported that some patients with CJD due to c-hgh treatment (called iatrogenic CJD) also had prematurely developed deposits of the amyloidbeta protein in their brains.
In a 2018 paper they went on to show that archived samples of the hormone, which were contaminated with amyloid-beta protein, could transmit amyloid-beta to mice.
This latest study, published in Nature Medicine, reports on eight people referred to UCLH’S
National Prion Clinic at the National Hospital for Neurology and Neurosurgery in London, who had all been treated with c-hgh in childhood, often over several years.
Five of them had symptoms of dementia, and either had already been diagnosed with Alzheimer’s disease or would otherwise meet the diagnostic criteria for this condition. Another person met criteria for mild cognitive impairment. These people were between 38 and 55 years old when they started having neurological symptoms.
Further tests supported the diagnoses of Alzheimer’s disease in two patients, and was
There is no risk that Alzheimer’s disease can be spread between individuals or in routine medical care Prof Jonathan Schott
suggestive of Alzheimer’s in oneotherperson.post-mortem analysisshowedsignsofalzheimer’s in another patient.
Researchers say the unusually young age at which these patients developed symptoms suggests they did not have the usualalzheimer’sthatisassociatedwitholdage.andinthefive patientsinwhomsampleswere availableforgenetictesting,the teamruledoutinheritedalzheimer’s disease.
Co-author Professor Jonathanschott,uclqueensquare Institute of Neurology, honorary consultant neurologist at UCLH, and chief medical officer at Alzheimer’s Research UK, said: “It is important to stress thatthecircumstancesthrough which we believe these individuals tragically developed Alzheimer’s are highly unusual, and to reinforce that there is no risk that the disease can be spread between individuals or in routine medical care.
“These findings do, however, provide potentially valuable insights into disease mechanisms, and pave the way for furtherresearchwhichwehope will further our understanding of the causes of more typical, late onset Alzheimer’s disease.”
The findings come after it was revealed a blood test could be just as accurate as painful and invasive lumbar punctures for detecting Alzheimer’s disease,.
Measuring levels of a protein called p-tau217 in the blood could be just as good at detectingthesignsofalzheimer’s,and betterthanarangeofothertests currently under development, experts determined earlier this month. The protein is a marker for biological changes that happen in the brain during Alzheimer’s disease.
The new findings have the potential to “revolutionise” diagnosis for people with suspectedalzheimer’s,expertssay. In the study of 786 people, the researcherswereabletousethe The Alzpath p-tau217 test to identify patients as likely, intermediate and unlikely to have Alzheimer’s disease.