Alzheimer’s disease pathology was observed in brain samples of individuals with Creutzfeldt-Jacob Disease suggesting possible human transmission
In a recent study published in Nature, a U.K group of scientists have unexpectedly discovered the presence of early-onset Alzheimer’s disease pathology in individuals with Creutzfeldt-Jacob Disease (CJD). CJD is a rare, rapidly progressive dementia that affects one in a million people worldwide and is characterized by microscopic holes in the brain at the time of death. As a prion disease, it can be transmitted to humans by exposure to affected brain tissue and CNS fluid, or inadvertently through medical treatment.
Amyloid-beta (Aβ), a protein that is the central component of Alzheimer’s disease pathology, was observed in autopsy brain samples of 7 out of 8 individuals aged 35-50 years who had acquired CJD from medical treatment. The presence of Aβ is rare at this age range and prompted the research group to examine other CJD cohorts for similar pathology or genes associated with early-onset Alzheimer’s disease. They reported that they did not observe Aβ or any genetic predisposition to Alzheimer’s in control prion disease groups used for comparison, and suggest that the Aβ pathology observed in these individuals had developed independently of CJD, possibly through incidental treatment.
The ‘prion-like’ transmission of Alzheimer’s disease and other neurodegenerative disorders has been of interest to scientists for a while and the experimental introduction of Aβ into the central nervous system of animal and primate models has been demonstrated using Alzheimer’s disease brain tissue. The authors of the current study state however that there is no evidence to support that Alzheimer’s disease is contagious or transmissible, but known routes of human prion transmission, including surgical instruments and blood transfusion activities, should be investigated thoroughly with regard to Aβ.
Jaunmuktane Z, Mead S, Ellis M, Wadsworth JD, Nicoll AJ, Kenny J, Launchbury F, Linehan J, Richard-Loendt A, Walker AS, Rudge P, Collinge J, Brandner S. Evidence for human transmission of amyloid-β pathology and cerebral amyloid angiopathy. Nature. 2015 Sep 10;525(7568):247-50.
National Institute of Neurological Disorders and Stoke site on Creutzfeldt-Jacob Disease: http://www.ninds.nih.gov/disorders/cjd/detail_cjd.htm
Written by Fiona Wong, PhD