Creutzfeldt-Jakob disease

What is Creutzfeldt-Jakob disease?

Creutzfeldt-Jakob disease (CJD) is a rare form of irreversible dementia that comes on fast. It is caused by infectious proteins called prions. Prions are proteins that are naturally in the brain and are normally harmless. When they are not shaped properly, however, they can have devastating effects. They can attack the brain, kill cells and create gaps or holes in brain tissue.

Prion diseases affect both humans and animals. Prion diseases were often in the news during the mid-1980s, with the bovine spongiform encephalopathy (BSE) epidemic (or, as it is more commonly called, ‘mad cow disease’). This is a prion disease of cattle. The best known prion disease in humans is Creutzfeldt-Jakob disease. It affects about one to two persons in a million worldwide each year, with about 35 new cases being diagnosed in Canada every year1.

There are two types of CJD: classic CJD and variant CJD (vCJD). The three types of classic CJD include:

  1. Sporadic: This type of CJD accounts for 90% of cases in Canada. It affects people between 45 and 75 years old. The cause of sporadic CJD is not known. The disease appears without warning. Most people with sporadic CJD die within one year.
  2. Familial or genetic: This type of CJD appears in families with an abnormal gene. It makes up 7 per cent of cases. Genetic testing can be done by a blood test. It can also be done after someone has died, by looking at the brain tissue. A person who has this abnormal gene has a 50 per cent chance of passing it on to his or her children. Gerstmann-Sträussler-Scheinker (GSS) and Fatal Familial Insomnia (FFI) are very rare forms of genetic CJD.
  3. Iatrogenic: Few people around the world get CJD from accidental transmission during a medical procedure such as: human pituitary hormone therapy, human dura-mater grafts, corneal grafts or instruments used in neurosurgery. Less than 1 per cent of people have this type of CJD.

Variant CJD affects younger people at an average age of 28 years. This form of CJD can develop from eating beef that was infected with BSE. Also, variant CJD has been reported to be transmitted by a blood transfusion from a person with variant CJD in the United Kingdom2.

There may be several years between the time a person is exposed to the disease and the first prions become misshapen, but once the symptoms do begin, the disease moves quickly.

How does Creutzfeldt-Jakob disease affect the person?

Classic CJD can look like many other dementias. It comes on quickly and the decline in thinking ability also moves quickly once symptoms appear.

The person may have:

  • Mood swings
  • Memory problems
  • A lack of interest and not act like himself
  • Rapidly progressing dementia with a loss of memory and thinking abilities
  • Difficulty with balance when walking
  • Clumsiness
  • Vision problems, including blindness
  • Stiff limbs
  • Muscle jerks or twitching
  • Difficulty speaking
  • Difficulty swallowing
  • “Akinetic mutism” (the person can move her eyes and seem alert, but cannot speak or voluntarily move)

People who are in the later stages of CJD lose awareness of their disease as it develops. This is seen in neurological (nerve) examinations. In the early stages of the disease, though, people with CJD can be quite scared, which can be very distressing. It is probably associated with visual hallucinations (seeing things that are not there). They may feel uncomfortable. Some of the symptoms of the disease, such as myoclonus (sudden jerking of the limbs) are also distressing for caregivers to see. There are medications and care strategies that can ease these symptoms and make the person more comfortable. For more information on the care of a person with CJD, visit the CJD Foundation website at

Coma and death
People with sporadic CJD generally live less than 12 months after the signs and symptoms appear, although some people may live as long as two years. Most people fall into coma before death. Death is usually a result of complications such as heart failure, respiratory (breathing) failure or pneumonia.

Symptoms of variant CJD are:

  • Depression, withdrawal and behaviour changes
  • Pain and odd sensations in the face or limbs
  • Difficulty walking
  • Progressive dementia
  • Inability to move or speak

People with variant CJD tend to live slightly longer — about 12 to 14 months after signs and symptoms appear.

How is Creutzfeldt-Jakob disease assessed?

Creutzfeldt-Jakob disease is very hard to diagnose, especially in the beginning of the disease. There is no test to diagnose CJD in a living person. The only way to tell if a person has CJD is to examine the brain tissue after death, during an autopsy. However, doctors will do a detailed exam and many tests to help diagnose this disease. The following steps may be taken:

  • Detailed medical history: This will help the doctor learn when the person's signs and symptoms started, because CJD develops so quickly.
  • CT scan (computerized tomography) takes a picture of the brain. It can be used to diagnose other diseases, as well.
  • MRI (magnetic resonance imaging) also takes a picture of the brain. It helps to tell the difference between sporadic CJD and variant CJD. It can also be used to find other diseases.
  • EEG (electroencephalogram) measures the electrical activity of the brain. Sometimes, but not always, there is a specific pattern on the EEG that helps to diagnose CJD.
  • Lumbar puncture: Using a needle and syringe, a doctor can take fluid from the person's spine. This is examined to rule out other infections of the brain. One of the tests is called the 14-3-3 protein. If the 14-3-3 is positive, it means that there has been some brain cell death, though this is not always because of CJD.
  • Blood tests: Blood tests are sometimes done to rule out other diseases and to see if there is a possibility of the genetic form of CJD. For a list of genetic counsellors in Canada visit the Canadian Association of Genetic Counsellors website:
  • Brain autopsy: The only way to confirm CJD is by looking at brain tissue with a microscope, after death. Brain autopsies are performed only in certain large hospitals in Canada. The CJD Surveillance System (see contact information at end) can help make arrangements for a brain autopsy if CJD is suspected and if the next of kin gives consent.

What are the risk factors for Creutzfeldt-Jakob disease?

Doctors do not know the true risk of developing either form of CJD. Right now, there is no specific way to protect someone from getting sporadic or familial CJD. However, certain factors may increase one's risk:

Pituitary hormone treatment: If pituitary hormone treatment taken from human tissue was used before the genetically engineered form of the hormone was available in the 1980s, there is an increased risk. Since 1985, human growth hormones have been man-made. This means the disease can no longer be transmitted this way.

Family history of CJD: A few people have a genetic mutation that increases their chances of developing the disease. A blood test or brain tissue examination after death can be done to find out if a person has the mutation.

Contaminated surgical instruments: A few people have been infected from contaminated instruments used during brain surgery. Today, instruments are destroyed if they were used on the brain of someone with possible CJD.

CJD precautions: These are infection control precautions that are needed only for certain medical procedures involving specific tissue. When embalming the remains of a person who has died of a possible prion disease, the World Health Organization and the Public Health Agency of Canada recommend that funeral workers use CJD precautions.

You cannot catch CJD by touching, feeding or taking care of a person with CJD at home. CJD is not a contagious disease transmitted by social or sexual contact, or by air. Since other infections can be spread that way, it is recommended that the following basic precautions be followed:

  • Wash your hands before eating or drinking.
  • Protect your hands and face from exposure to the affected person's blood or body fluids.
  • Cover cuts or wounds with waterproof bandages.
  • Blood transfusions: The Canadian Blood Services and Héma-Québec do not allow people who have CJD to give blood.

For variant CJD only: Eating beef from countries with a relatively high rate of transmissible spongiform encephalopathy (TSE) may increase risk. To help reduce the risk of getting CJD from infected beef, think about the following options:

  • Be selective when eating beef in parts of the world where they are not as strict about quality.
  • Do not eat the highest risk parts of cattle, such as eyes, brain, spinal cord and intestines.

Is there treatment?

There is no known cure for CJD yet. There is no effective way to slow its progression. It is important to relieve pain, discomfort and other symptoms such as jerking movements and unsteadiness. Supportive nursing care is focused on keeping the person as comfortable as possible.

For more information

Contact your regional Alzheimer Society.
More information can be obtained from the following:

  1. The Public Health Agency of Canada's (PHAC) Creutzfeldt-Jakob Disease Surveillance System (CJDSS) study team. The CJDSS conducts active monitoring of CJD in Canada. Its main purpose is to study human prion diseases in Canada and to protect public health by reducing the risk of transmitting prions. The CJDSS has a 24-hour service to make arrangement for brain autopsies of persons suspected of having CJD. More information about the CJDSS can be found at or call toll free: 1-888-489-2999.
    You can also read the spring 2013 issue of the newsletter CJD in Canada: Family Edition.
  2. Canadian Food Inspection Agency, BSE Fact Sheet or website.
  3. Prionet Canada
  4. CJD Foundation (US) or toll free: 1-800-659-1991.
  5. CJD Support Network (UK)
  6. CJD Support Network (Australia)
  7. European Collaborative Study Group of CJD (EuroCJD)
  8. University of California, San Francisco
  9. Health Ontario (Ministry of Health and Long Term Care, Ontario)
  10. Canadian Association of Genetic Counsellors
  11. World Health Organization (WHO): WHO infection control guidelines for transmissible spongiform encephalopathies. Report of a WHO consultation, Geneva, Switzerland, 23–26 March 1999. Geneva, World Health Organization, 2000.


  1. Public Health Agency of Canada (2007). CJD and human prion diseases.
  2. Brown, P. (2007). Creutzfeldt-Jakob disease: reflections on the risk of blood product therapy. Haemophilia, 13, 5. p. 33–40.

[The contents of this document are provided for information purposes only, and do not represent advice, an endorsement or a recommendation, with respect to any product, service or enterprise, and/or the claims and properties thereof, by the Quebec Federation of Alzheimer Societies.]

Last Updated: 11/26/2013