What Are Prion Diseases?

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What Are Prion Diseases? 

Prion disease is an umbrella term used to refer to a rare group of brain disorders that affect both humans and animals. This makes it possible for the disease to spread from animal to people and, in some instances, from human to human.

These diseases are caused by the prion protein, which can be found in your tissues and brain. Some researchers believe that normal prion proteins protect the brain from damage. Abnormally shaped prion proteins, however, are infectious and can cause diseases.

Researchers don’t completely understand why abnormal prion proteins form. Prion diseases are also known as transmissible spongiform encephalopathies (TSEs). These diseases are incredibly rare, and only about 300 cases are diagnosed in the United States every year. Abnormal prion proteins are capable of infecting normal prion proteins—this can turn them into defective proteins that cause disease.

Symptoms of Prion Diseases 

Symptoms of prion diseases vary depending on what type of prion disease you have. However, in general, they tend to be fatal and, in many cases, have high mortality rates. Some of the most common symptoms that many prion diseases share include: 

  • Confusion 
  • Fatigue 
  • Hallucinations 
  • Dementia
  • Trouble walking 
  • Changes in your posture
  • Trouble speaking 
  • Muscle stiffness 
  • Personality changes 
  • Diminished memory 
  • Involuntary muscle spasms
  • Tremors
  • Seizures

Identifying Prion Diseases 

More research needs to be done into prion diseases to fully understand how they affect humans. These diseases are notoriously hard to diagnose and can be incredibly deadly. The most common way to confirm if a person has prion disease is by doing a biopsy after death.

Doctors and healthcare providers typically run several tests to rule out any other conditions in suspected cases of prion diseases. When people suddenly develop dementia, and it progresses rapidly (sometimes over the course of days or weeks), prion diseases are typically considered a likely culprit. Some of the tests done to help identify if you have a prion disease include: 

  • Blood tests 
  • An electroencephalogram (EEG): This is a test that records the electrical activities in your brain. Abnormal activities could point to problems like prion diseases. 
  • An MRI: An MRI is done to look at your brain for any changes in structure that prion diseases could have caused. 
  • A spinal tap: This is when a doctor takes a sample of cerebrospinal fluid (CSF), which surrounds the brain and spinal cord, and tests it for diseases or signs of disease.
  • Urine tests

Causes of Prion Diseases 

Prion diseases are caused by abnormal prion proteins forming in clumps on the brain. This, in turn, causes brain damage and results in neurodegenerative conditions. However, it’s unclear what causes these proteins to become abnormal. Abnormal prion proteins cause prion diseases by either self-replicating or being transmissible. This can then cause cells in the brain to die.

Certain factors put people at a higher risk of developing prion diseases than others. They include: 

  • Eating meats that have been affected by a prion disease like “mad cow disease” 
  • Being infected by medical equipment 
  • Having a family history of prion diseases 

Types of Prion Diseases 

Prion diseases affect both humans and animals. In some cases, prion diseases that affect animals could be transmitted to humans too. 

Human Prion Diseases 

The two most common forms of human prion diseases include: 

  • Creutzfeldt-Jakob Disease (CJD): CJD is a fatal neurodegenerative condition. It progresses rapidly and is thought to lead to death within a year after infection occurs. It typically develops around age 60. It can either be inherited from a parent or develop on its own. It affects one in one million people across the globe yearly. CJD could either be genetic, acquired, or sporadic. 
  • Variant Creutzfeldt-Jakob Disease (vCJD): This variant of CJD appears to affect younger people. Symptoms of the disease include muscle spasms, confusion, and poor muscle coordination. Some research shows that people with this variant could die around 13 months after exhibiting symptoms. This condition is related to a condition called “mad cow disease.” You can potentially get this condition by eating meat that has been infected.

Other rare human prion diseases are: 

  • Kuru 
  • Gerstmann-Straussler-Schneiker Syndrome 
  • Fatal Familial Insomnia (FFI)
  • Variably protease-sensitive prionopathy (VPSPr)

Is Alzheimer's Disease a Prion Disease?

There is a common misconception that Alzheimer's is a prion disease. This is because they are both neurodegenerative disorders that are linked to the build-up of abnormal proteins on the brain which causes damage. However, while prion disease is linked to the abnormal build-up of prion proteins, Alzheimer's is linked to the abnormal build-up of proteins called amyloid plaques.

Animal Prion Diseases 

The most common animal prion diseases include: 

  • Scrapie: Scrapie is a neurodegenerative disease that affects sheep and goats. Some research shows that it mostly affects black-faced sheep in the United States. There is also no evidence that the disease can be passed from one species to another.
  • Chronic Wasting Disease (CWD): This is a form of prion disease that affects a class of animals known as cervids. Cervids include animals such as deers and moose. While humans can’t get CWD, other primates like monkeys can. Regardless, it’s important to avoid animals that look sick or might be suspected to have CWD. 
  • Bovine Spongiform Encephalopathy (BSE): This is also known as "mad cow disease." It’s the only type of animal prion disease transmissible to humans. 

Other less common animal prion diseases include: 

  • Transmissible mink encephalopathy 
  • Ungulate spongiform encephalopathy 
  • Feline spongiform encephalopathy 

Treatment for Prion Diseases 

There’s currently no cure for prion diseases. However, there is ongoing research into developing effective treatments for the diseases. The focus of treatment is to make a person who has the condition as comfortable as possible as they live with the disease’s debilitating symptoms.

Slowing Disease Progression and Alleviating Symptoms

Treatment also aims to slow the rate at which the disease progresses. In specific scenarios, opiate drugs might be prescribed to relieve pain. A medication like Klonopin (clonazepam) may also be prescribed to help with symptoms like involuntary muscle spasms.

Preventing Prion Diseases

It’s also possible to prevent prion diseases. Making sure medical pieces of equipment are properly cleaned and sterilized is an excellent first step.

Also, being careful of the kinds of animal meat you consume and where you get it from is essential. Regulatory bodies are also closely monitoring how cows are fed to ensure that they don't get infected with prion diseases that can be spread to humans.

Coping With Prion Diseases 

Prion diseases are fatal and deadly. Most of its treatment features support for as long as the person has the condition. If you have just been diagnosed with a prion disease, it’s essential to start thinking about end-of-life care.

It’s advisable to give directives to your close family and friends on what to do when you can no longer support yourself and in the event of your passing.

A Word From Verywell

Prion diseases are a rare brain disorder which means the odds of you getting a prion disease is very low. You can also prevent prion diseases by avoiding eating meats from sources you don't trust, and getting medical procedures done in a trusted healthcare facility.

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14 Sources
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  1. Onodera T, Sakudo A. Introduction to current progress in advanced research on prions. Current Issues in Molecular Biology. Published online 2020:63-66.

  2. National Institute of Allergy and Infectious Diseases. Prion Diseases.

  3. John Hopkins Medicine. Prion Diseases.

  4. Kübler E, Oesch B, Raeber AJ. Diagnosis of prion diseases. British Medical Bulletin. 2003;66(1):267-279.

  5. Stanford Healthcare. Diagnosis of Prion Diseases.

  6. MSD Manual Professional Edition. Overview of prion diseases - neurologic disorders. July 2020

  7. Creutzfeldt-Jakob Disease Foundation. Types of prion diseases.

  8. US Food Drug and Administration (FDA). Bovine spongiform encephalopathy (Bse) questions and answers.

  9. Kellett KAB, Hooper NM. Prion protein and Alzheimer's disease. Prion. 2009;3(4):190-194.

  10. MSD Veterinary Manual. Overview of scrapie - nervous system.

  11. Wyoming Department of Health. Prion diseases.

  12. Oregon Health & Science University (OHSU). Prion Diseases.

  13. National Institute of Neurological Disorders and Stroke. Creutzfeldt-jakob disease fact sheet.

  14. Stanford Healthcare. Prevention of Prion Diseases.