What are prion diseases?
Prion diseases comprise several
conditions. A prion is a type of protein that can trigger normal proteins in the brain
to fold abnormally. Prion diseases can affect both humans and animals. They are
sometimes spread to humans by infected meat products. In many cases, the source of the
abnormal protein is unknown. The most common form of prion disease that affects humans
is Creutzfeldt-Jakob disease (CJD).
Prion diseases are rare. About 300 cases are reported each year in the U.S.
Types of prion diseases include:
CJD. A person can inherit this
condition. In that case, it's called familial CJD. Sporadic CJD, on the other hand,
develops suddenly without any known risk factors. Most cases of CJD are sporadic.
They tend to strike people around age 60. Acquired CJD is caused by exposure to
infected tissue during a medical procedure, such as a cornea transplant. Symptoms of
CJD (see below) quickly lead to severe disability and death. In most cases, death
occurs within a year.
Variant CJD. This is an infectious
type of the disease. It is related to “mad cow disease.” Eating diseased meat may
cause the disease in humans. The meat may cause normal human prion protein to develop
abnormally. This type of the disease often affects younger people.
sensitive prionopathy (VPSPr). This is
also extremely rare. It is like CJD. But the protein is less sensitive to digestion.
It is more likely to strike people around age 70 who have a family history of
Sträussler-Scheinker disease (GSS). This type is extremely
rare. It occurs at an earlier age, typically around age 40.
Kuru. This disease is seen in New Guinea. It's caused by eating human brain tissue contaminated with infectious prions. Because of increased awareness about the disease and how it is transmitted, kuru is now rare.
Fatal insomnia (FI). This is a rare
hereditary disorder. It causes trouble sleeping. There is also a sporadic form of the
disease that is not inherited.
What causes prion disease?
Normal prion protein is found on
the surface of many cells. Prion diseases occur when this protein becomes abnormal and
clumps in the brain. It then causes brain damage. This abnormal buildup of protein in
the brain can lead to memory problems, personality changes, and trouble with movement.
Experts still don't know a lot about prion diseases. But unfortunately, these disorders
are often fatal.
Who is at risk for prion diseases?
You may be at risk for prion diseases if you:
- Have a family history of prion
- Eat meat infected by “mad cow
- Are infected by contaminated corneas
or medical equipment
What are the symptoms of prion diseases?
Symptoms of prion diseases include:
- Rapidly developing dementia
- Difficulty walking and changes in
- Jerking movements of the muscles
- Muscle stiffness
- Difficulty speaking
How are prion diseases diagnosed?
Prion diseases are confirmed by
taking a sample of brain tissue during a biopsy or after death. But given the risks of a
brain biopsy, a number of other tests are often done instead. These can help diagnose
prion diseases such as CJD or rule out other diseases with similar symptoms. Prion
diseases should be considered in all people who have dementia that is quickly getting
The tests include:
- MRI scans of the brain
- Spinal tap (lumbar puncture) to take
samples of fluid from the spinal cord
- Electroencephalogram, a painless test
that looks at brain waves by placing electrodes on the scalp
- Blood tests
- Nervous system and visual exams to
check for nerve damage and vision loss
- Genetic tests to look for known hereditary causes of prion
disease. This is especially important if other family members are affected
How are prion diseases treated?
Prion diseases can't be cured. But
certain medicines may help slow their progress. Medical care focuses on keeping people
with these diseases as safe and comfortable as possible, despite worsening and
Can prion diseases be prevented?
Properly cleaning and sterilizing
medical equipment may prevent the spread of the disease. If you have or may have CJD,
don't donate organs or tissue, including corneal tissue. Newer regulations that govern
the handling and feeding of cows may help prevent the spread of prion diseases.
Living with prion diseases
As prion diseases progress, people
with these diseases generally need help taking care of themselves. In some cases, they
may be able to stay in their homes. But they eventually may need to move to a care
Key points about prion diseases
- Prion diseases are very rare.
- Symptoms can progress rapidly requiring help with daily needs.
- Prion diseases are always fatal.
Tips to help you get the most from a visit to your healthcare provider:
- Know the reason for your visit and what you want to happen.
- Before your visit, write down questions you want answered.
- Bring someone with you to help you ask questions and remember what your provider tells you.
- At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
- Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
- Ask if your condition can be treated in other ways.
- Know why a test or procedure is recommended and what the results could mean.
- Know what to expect if you do not take the medicine or have the test or procedure.
- If you have a follow-up appointment, write down the date, time, and purpose for that visit.
- Know how you can contact your provider if you have questions.