CJD and Alzheimer’s?

According to new research, the brains of Creutzfeldt-Jakob disease (CJD) victims show evidence of Alzheimer’sCreutzfeldt-Jakob disease pathology.  However, neuroscientists have dismissed concerns that people can “catch” Alzheimer’s by becoming infected with the “seeds” of the condition through surgery with contaminated instruments or blood transfusions.  The study, published in Nature last week, reported autopsy results from the brains of eight people between 36 and 51 years old who died of CJD after receiving contaminated growth hormone injections.  In four subjects, there was evidence of moderate to severe amyloid-ß pathology, one of the abnormal proteins associated with Alzheimer’s.

None of the patients in-question carried genes known to be associated with early-onset Alzheimer’s, and none had shown any symptoms of the condition.  The researchers also analyzed pituitary glands from the individuals with amyloid-ß brain pathology and found marked amyloid-ß deposition in numerous cases.

Around 450 people around the world have died from CJD after receiving treatment, typically in childhood, with growth hormone harvested from pituitary glands contaminated with prions.  This treatment ceased 30 years ago after the risks of CJD became known.  The researchers behind the study say that in addition to CJD, their findings suggest that healthy exposed individuals could also be at risk of iatrogenic Alzheimer’s disease.  They cite another study, published in Brain back in August, as evidence that prion disease itself doesn’t appear to predispose an individual to Alzheimer’s disease.  The study showed minimal to no amyloid-ß pathology at autopsy in 116 patients with other prion diseases, who were of a similar age or a decade older and didn’t cary the APOE ε4 allele.

However, several neuroscientists have questioned the conclusion drawn by the researchers.  Masud Husain, professor of neurology and cognitive sciences at the University of Oxford, has said that stronger evidence is necessary to accept this proposal.  David Allsop, a professor of neuroscience at the University of Lancaster, has dismissed the conclusion as an extrapolation, and suggests that the results are most likely due to a deposition of CJD’s “prion protein” resulting in the co-accumulation of ß amyloid.  Chief medical officer Dame Sally Davies has also said that there’s no evidence that Alzheimer’s can be transmitted in humans or through any sort of medical procedure.

If you’d like to learn more about the study, click here!