Prion Disease

Prion disease is a group of rare, terminal neurodegenerative diseases. They happen when proteins in your brain turn into abnormal proteins known as prions. Prion disease causes brain damage that leads to dementia. Healthcare providers focus on treatments, including medication, to manage symptoms.


What is prion disease?

Prion disease is a group of very rare neurodegenerative diseases that can affect humans and animals. Prion disease happens when normal proteins in your brain turn into abnormal proteins known as prions (pronounced “PREE-ons”).

Prion disease (sometimes called transmissible spongiform encephalopathy) causes brain damage that leads to dementia. These symptoms develop suddenly and worsen quickly. It’s rare, affecting about 1 in 1 million people worldwide.

Prion diseases are terminal illnesses. Healthcare providers focus on treatments, including medication, to manage symptoms. Providers also help people cope with the ways prion disease changes their lives and the lives of those around them.


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How do people get prion disease?

You can get prion disease by inheriting a genetic mutation (familial prion disease) or by being infected by the disease (acquired prion disease). But the condition typically happens even when you don’t have a genetic mutation or exposure to prion infection. Researchers and healthcare providers call this sporadic prion disease.

Sporadic prion diseases

In sporadic prion disease, normal proteins turn into prions for no known reason. Sporadic prion diseases include:

  • Creutzfeldt-Jakob disease (CJD): This is the most common type of sporadic prion disease, accounting for 85% of all cases.
  • Sporadic fatal insomnia: A very rare form of sporadic prion disease, even less common than fatal familial insomnia.
  • Variably protease-sensitive prionopathy: This is another very rare form of sporadic prion disease.

Familial prion diseases

These prion diseases develop when the PRNP gene mutates, creating an abnormal protein. People may develop a familial prion disease by inheriting one mutated gene from either biological parent (autosomal dominant inheritance). There are more than 50 different PRNP mutations that can cause different inherited prion diseases. Familial prion diseases include familial Creutzfeldt-Jakob disease (CJD) and two CJD subtypes:

  • Gerstmann-Sträussler-Scheinker (GSS) syndrome: This condition is extremely rare and affects between 1 and 10 people out of every 100 million worldwide.
  • Fatal familial insomnia: This condition is even rarer than GSS syndrome. There are about 50 to 70 families in the world who carry the mutation that causes the disease. Other prion diseases with PNRP gene mutations have also been described, including British kindred (group of family members) of 11 people who developed diarrhea, sensory autonomic neuropathy, seizure and dementia. Autonomic neuropathy affects your blood pressure, heart rate and your ability to control when your poop (bowel incontinence) and pee (urinary incontinence).

Acquired prion disease

Acquired prion disease can happen if people are exposed to contaminated food or medical equipment. This is the least common way that people develop the condition. Kuru is the first transmissible neurodegenerative disorder identified and studied. This occurred among the Fore people of Papua New Guinea and is believed to be transmitted from person to person by ritual cannibalism.

What is the deadliest prion disease?

All prion diseases are deadly, meaning people die from the disease. Typically, people with prion disease live a few months up to three years after they develop symptoms.

Symptoms and Causes

What are prion disease symptoms?

Prion disease symptoms vary depending on the specific disease and how it affects your brain. In general, people with prion disease have neurologic issues that get worse. Common prion disease symptoms include:

What are complications of prion disease?

Prion disease complications come in a cascade of issues that not only affect the person with the disease, but also the family members and friends who care for that person.

Prion disease complications may develop within a few months to a year from when someone first had symptoms. Complications may include:

  • Losing the ability to take care of oneself.
  • Dementia.
  • Mutism.
  • Coma (final stage).

When someone has prion disease, they quickly become more dependent on their family and other people who care for them. Family and others become caretakers, doing what they can to help their loved one manage.

At the same time, caretakers live with watching their loved one lose important abilities like being able to remember information or communicate. Their loved one’s personality may change or they may develop psychological issues.


What causes prion disease?

Prion disease starts when the normal prion protein (PrPc) in your brain turns into an abnormal misfolded form (PrPSc) known as prions. The abnormal prions clump together or bind with normal prion proteins to make more prions. Over time, the abnormal prions damage or destroy nerve cells in your brain and you begin to lose brain function, like the ability to walk, think or communicate as you did before you became ill.

Diagnosis and Tests

How is prion disease diagnosed?

Healthcare providers may do the following tests to diagnose prion disease:

  • Blood tests and lumbar puncture: People who have the genetic mutation that causes prion disease may participate in tests to find biomarkers. Biomarkers are substances in your blood or cerebrospinal fluid that indicate damage or disease. Cerebrospinal fluid is the clear liquid that surrounds your spine and brain.
  • Brain MRI: This test provides very clear images of your brain so providers can look for signs of prion disease.
  • Electroencephalogram (EEG): This test measures brain activity.
  • Real-time quaking-induced conversion assay (RT-QuIC): In this test, pathologists look for prions in cerebrospinal fluid.


Management and Treatment

Is there a cure for prion disease?

Unfortunately, healthcare providers don’t have treatments to cure or slow down prion diseases. Prion diseases are life-threatening. Most people with prion disease die within a few months to a few years after they receive a diagnosis.

Treatment emphasizes palliative care to manage symptoms so people are as comfortable as possible. For example, providers may prescribe:

Outlook / Prognosis

What is the outlook for prion diseases?

Right now, there’s no cure or treatment for prion diseases. But researchers are making progress on two fronts that may lead to early diagnosis and treatment. The RT-QuIC test helps detect prion disease before it does irreversible brain damage. And researchers are studying prions for ways to stop abnormal protein development and to keep normal ones from turning into abnormal ones.

Living With

What can I expect if I have prion disease?

Prion disease moves quickly, which can make it hard for you to take care of yourself. If you have this disease, you may want to complete an advance directive form.

Advance directives are legal documents. Advance directive examples include:

  • Living wills: This document describes what you want to happen if you have a terminal illness like prion disease.
  • Durable power of attorney for healthcare (DPA): You use this document to identify who will make healthcare decisions for you if you’re no longer able to speak for yourself.

What should I do if a family member has a familial prion disease?

Sometimes, people inherit genetic mutations that increase the chance they’ll get prion disease. Genetic tests will determine if you’re carrying one or more of the genetic mutations that cause prion disease. The tests may indicate your specific risk.

Having genetic testing for a terminal illness is a personal decision. Some people don’t want to know if they’re at risk. If you do want genetic testing, ask a healthcare provider for a referral to the National Prion Disease Pathology Surveillance Center, which oversees genetic testing for prion disease.

How do I take care of my family member with prion disease?

These illnesses upend daily life. In addition to dealing with the shock and grief that someone you love has a terminal illness, you need to plan for how you’ll care for your family member. Here are some suggestions:

  • Develop a care plan: Depending on your situation, your family member may need care in a residential facility or home-based care that relies on family, friends and private health aides. Your loved one may need help with daily activities like going to the bathroom or eating.
  • Set up hospice care: Prion disease is a terminal illness with symptoms that come on suddenly and get worse very quickly. Arranging hospice care before your loved one needs it means it will be available as soon as they need it.
  • Create a soothing environment: People with prion disease often are unusually sensitive to sudden unexpected activity, like being touched, loud sounds or even being around large groups of people. They may get upset or agitated. Managing their environment can help keep them calm and relaxed.

When should I see my healthcare provider?

Prion disease symptoms typically get worse very fast. If you or someone in your family has prion disease, you’ll work with healthcare providers to manage the disease’s impact.

What questions should I ask my healthcare provider?

It may have been devastating to learn you or someone in your family has prion disease. You and your family probably have many questions now and will have more questions as the disease progresses. Here are some questions that may help you begin to understand what you can expect:

  • How do you know I have prion disease?
  • What prion disease do I have?
  • How will it affect me?
  • What should I do next?
  • What can I do to take care of my family member?
  • Should my family have genetic counseling and tests?

A note from Cleveland Clinic

Prion disease is a group of rare, terminal illnesses that affect your brain. Prion disease symptoms may come on suddenly and quickly get worse. It may be devastating to learn you or someone you love has a disease for which there’s no cure or treatment to slow it down. But there are treatments to relieve symptoms. And there are programs and services to help people that prion disease affects, including caretakers. If you or someone you love has a prion disease, don’t hesitate to ask questions and to ask for help.

Medically Reviewed

Last reviewed on 01/21/2024.

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