Prion diseases are an extremely rare group of disorders that damage brain and nervous system tissues and function. They cause symptoms that rapidly worsen. At the OHSU Brain Institute, we offer:
- A team of skilled professionals who can treat symptoms and provide support to you and your family.
- Treatments including muscle-relaxing and anti-seizure medications.
- Coordination with our palliative care and social services providers to help patients and their families.
Understanding prion diseases
What are prion diseases?
Abnormal proteins: Prion diseases occur when prion protein, found throughout the body, begins folding into an abnormal three-dimensional shape.
Effects: The damaged prion protein destroys brain cells, leading to a rapid decline in thinking and reasoning. Patients may also experience:
- Involuntary muscle movements
- Difficulty walking
- Mood changes
Prion diseases, because they cause spongelike holes in brain tissue, are also called transmissible spongiform encephalopathies. They are not curable, though symptoms can be treated.
Creutzfeldt-Jakob disease, or CJD, is the most common prion disease. It progresses rapidly and is fatal, usually within a year.
Unknowns: Much about prion disease is unknown. Many cells, including brain cells, have normal forms of prion protein on their surface. Scientists don't understand its normal function nor what causes it to become misshapen.
The diseases affect both humans and animals. They can spread between humans and animals but not from one person to another.
Who gets prion diseases?
Most cases have no known cause, though a family history is a risk factor. A very small number of cases have been linked to eating meat infected with bovine spongiform encephalopathy, commonly known as "mad cow disease," and to contaminated medical equipment.
Some researchers believe an unusual "slow virus" or another organism causes Creutzfeldt-Jakob disease. They've been unable to isolate any kind of organism in people with the disease, however.
How rare are prion diseases?
Prion diseases are extremely rare. Sporadic Creutzfeldt-Jakob disease represents about 85 percent of all cases and affects an estimated one person per million worldwide a year. That translates into 320 new cases a year in the United States.
Symptoms can progress rapidly. They may include:
- Rapidly developing dementia
- Difficulty walking and changes in gait
- Personality changes and impaired memory
- Muscle stiffness
- Difficulty speaking
Types of prion diseases
Creutzfeldt-Jakob disease has several forms:
- Sporadic CJD develops spontaneously for no known reason, typically in people ages 60 to 65.
- Familial CJD affects people who inherited a gene mutation from a parent. It accounts for about 10 to 15 percent of cases. Some genetic types appear in people ages 20 to 40.
- Acquired CJD, including Variant Creutzfeldt-Jakob disease, or vCJD, results from exposure to an outside source of abnormal prion protein. These forms of prion disease account for about 1 percent of CJD cases. The most common sources, all extremely rare, are:
- Eating meat infected by bovine spongiform encephalopathy
- Infection from receiving contaminated corneas
- Infection from contaminated medical equipment
Other seldom-seen forms of prion disease are:
- Variably protease-sensitive prionopathy, similar to CJD but more likely to strike people around age 70 who have a family history of dementia.
- Familial fatal insomnia, which affects the area of the brain that controls sleep.
- Kuru, spread by cannibalism or other contact with the tissue of infected people.
- Gerstmann-Straussler-Scheinker syndrome, a progressive brain disorder that is almost always inherited.
Animal prion diseases include:
- Bovine spongiform encephalopathy, also called mad cow disease; this is the only type that can spread to humans.
- Chronic wasting disease
- Transmissible mink encephalopathy
- Feline spongiform encephalopathy
- Ungulate spongiform encephalopathy (found in deer and related animals)
Prion diseases typically can be confirmed only by taking a sample of brain tissue during a biopsy or after death.
Tests for Creutzfeldt-Jakob disease include:
- Exams to look for changes in brain functioning and vision.
- A spinal tap (also called a lumbar puncture) to withdraw a sample of cerebrospinal fluid, the liquid that bathes the brain and spinal cord. The fluid can show protein patterns that may indicate whether CJD or more common causes of dementia are present.
- An electroencephalogram, or EEG, to record the brain's electrical pattern. Patients with CJD and vCJD show an abnormal pattern.
- Magnetic resonance imaging, or MRI, scans can reveal brain patterns that point to CJD.
At the OHSU Brain Institute, we focus on treating symptoms and offering support to families coping with CJD.
- Muscle-relaxing medications and anti-seizure drugs can offer relief.
- Mood-stabilizing medications can help with irritability or mood changes.
- Our experts in palliative care and social services can help patients and their families manage comfort and other issues.
Scientists are working to develop tests for CJD.
One detects a protein marker in cerebrospinal fluid that indicates a loss of neuron structure or function. This test, not yet widely available, can help doctors diagnose the disease in people who are showing symptoms.
In 2014, researchers disclosed a technique that involves examining neurons collected from inside the nose using a sterile brush. The test correctly identified 30 of 31 CJD patients and showed negative results for all 43 without the disorder.