Researchers Confirm That Proteins from Neurodegenerative Diseases Are Not Contagious
A new paper, published in the online journal JAMA Neurology, reveals that proteins formed in neurodegenerative disorders and not infectious and cannot be transmitted between humans or from animals to humans. This comes as an answer to concerns regarding the contagiousness of neurodegenerative disorders. The study is led by a team of researchers from the Perelman School of Medicine, from the University of Pennsylvania, in the United States, in collaboration with scientists from the United States Centers for Disease Control.
According to previous studies of the matter, pathological proteins that are related with both the onset and the progression of several neurodegenerative diseases are able to spread to neighboring brain cells, thus being able to affect more than one region of the brain. The recently published study reports no evidence that supports the concern that these pathological proteins are contagious in any way. The ability of the proteins to spread from one cell to another is one of the possible pathways for progression in Alzheimer’s disease and possibly in Parkinson’s disease. The progression of other neurodegenerative disorders linked to pathological protein spread include ALS (amyotrophic lateral sclerosis) and FTLD (frontotemporal lobar degeneration).
Researchers say that the neurons that are affected by these misfolded proteins become dysfunctional. Further spread of these proteins causes the progression of neurodegenerative diseases because they affect an increasing number of neurons from different regions of the brain. “By interrogating an existing database with information on a cohort of well-characterized patients, we were able to determine that there is no evidence suggesting the pathology of Alzheimer’s or Parkinson’s can transmit between humans”, said professor John Trojanowski, the senior author of the study.
To be able to verify the contagiousness of these proteins, the research team gathered and analyzed data from an already existing cohort of patients. These patients had previously received hGH (human growth hormone) taken from the pituitary glands of cadavers. More than 7,700 patients received this hormone over more than 20 years (from 1963 to 1985). In 1985, approximately 200 patients developed CJD (Creutzfeldt-Jakob disease) due to an unwittingly contamination with prion proteins found in the pituitary tissue that was taken from the cadavers. CJD is a neurodegenerative disorder that is both incurable and invariably fatal. Sometimes CJD is referred to as a human form of BSE (bovine spongiform encephalopathy). The brain of patients suffering from CJD develops a sponge-like texture due to holes that form in the tissue.
All the patients in the cohort were followed up in order to track any other abnormalities caused by prions. For their study, the researchers investigated the extensive medical history of the patients, in search for signs that would indicate an increased risk for Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis or frontotemporal lobar degeneration. Researchers report that they found no evidence that any of the patients from the cohort developed Alzheimer’s, Parkinson’s or frontotemporal lobar degeneration. However, 3 patients have been found to have developed amyotrophic lateral sclerosis despite the fact that no ALS-related proteins were found. Proteins related to Alzheimer’s and Parkinson’s were found in patients, but weren’t significant.
Researchers concluded that even though the patients from the cohort were exposed to these pathological proteins, the diseases were not transmitted from one person to another. “This cohort is an invaluable resource and should continue to be followed, especially as we rapidly increase our understanding of disease progression in neurodegenerative conditions”, concluded the lead author of the study, Dr David Irwin.