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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 year 1.

There are two types of CJD:

  • classic CJD
  • variant CJD (vCJD)


The three types of classic CJD include:

  • 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.
  • 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.
  • 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 Kingdom 2.

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.

Read more about CJD here

Source: Alzheimer Society Canada - Last Updated 12/07/13