Prions are abnormal and infectious forms of proteins that collect in brain tissue, causing cells to die. The sponge-like holes left in the brain are a hallmark of transmissible spongiform encephalopathies such as bovine spongiform encephalopathy (BSE, also known as mad cow disease in cows and Chronic Wasting Disease¹ in deer and elk) and Creutzfeldt-Jakob disease² (CJD), the human version of BSE.

Both BSE and CJD are the result of a prion infection; both are untreatable and always fatal. Sporadic CJD (sCJD), a form that appears without known risk factors, accounts for nearly 85% of diagnosed CJD cases:^3,4

CJD is difficult to diagnose, as taking a brain biopsy to rule out a disease is impractical. However, in 2018, the National Institutes of Health published work from colleagues at the University of California San Diego and San Francisco, showing you can measure the distribution and level of prions in the human eye.⁵

According to Dr. Christina J. Sigurdson, professor of pathology at UC San Diego and Davis, who was on the team,⁶ “Our findings have implications for both estimating the risk of sCJD transmission and for development of diagnostic tests for prion diseases before symptoms become apparent.”

Alzheimer’s Disease Linked to Prions

For a number of years now, researchers have theorized and found evidence suggesting Alzheimer’s disease may in fact be a type of prion-based disease,^7,8,9 capable of being contracted via meat¹⁰ and transmitted via certain invasive medical procedures.¹¹

Researchers have noted that Alzheimer’s behaves like a slow moving version of CJD,^12,13,14and according to one paper,¹⁵ “Prions are considered a subclass of amyloids in which protein aggregation becomes self-perpetuating and infectious.” As reported by Scientific American:¹⁶

“Between 1958 and 1985, a number of individuals with short stature received shots of human growth hormone extracted from the pituitary glands of cadavers… Some of these samples were contaminated with prions that caused certain patients to develop Creutzfeldt-Jakob disease (CJD), a rare and fatal brain disorder. 

Treatments ceased once these reports came to light, but by that time an estimated 30,000 people had already received the injections. As of 2012, researchers have identified 450 cases of CJD worldwide that are the result of these growth hormone injections and other medical procedures, including neurosurgery and transplants.”

Previous animal research¹⁷ has also found that when tiny amounts of amyloid-beta proteins — which are a hallmark of Alzheimer’s — are injected into mice or monkeys, they act as self-propagating “seeds,” unleashing a chain reaction of protein misfolding that results in pathology that is very reminiscent of that seen in Alzheimer’s patients.

As Many as Half of Alzheimer’s Patients Have Prion-Like Proteins

Mounting research reveals a compelling link between a protein known as TDP-43 and neurodegenerative diseases such as Alzheimer’s, Parkinson’s and Lou Gehrig’s disease. TDP-43 behaves like the prions responsible for the brain destruction seen in Mad Cow and Chronic Wasting Disease.¹⁸

According to research¹⁹ published in 2011, TDP-43 pathology is detected in 25% to 50% of Alzheimer’s patients, particularly in those with hippocampal sclerosis, characterized by selective loss of neurons in the hippocampus, which is associated with memory loss.

Research presented at the 2014 Alzheimer’s Association International Conference also revealed Alzheimer’s patients with TDP-43 were 10 times more likely to have been cognitively impaired at death than those without it.^20,21