Types of CJD

There are four types of CJD: Fact sheets on each type can be downloaded by clicking on the headings below. Click here to view all of our fact sheets. 

Sporadic CJD (or classical CJD) is the most common form, accounting for around 85 per cent of cases. The cause is unknown. It mainly affects the over 50s and has a rapid onset. The course of the disease is usually measured in months.

Genetic CJD (sometimes known as famillal CJD) is an inherited form of the disease, with younger onset and a longer time course than sporadic CJD.

Iatrogenic CJD occurs through contamination with infected tissue via medicalprocedures, for example, the use of human growth hormone, blood transfusionor surgical instruments.

Variant CJD is caused by exposure to bovine spongiform encephalopathy, or BSE , and typically affects younger people. It has a relatively longer time course - an average 14 months from onset of symptoms to death. There is a combination of psychiatric, neurological and physical symptoms.

Symptoms of CJD

  • The precise symptoms and clinical time course of CJD vary according to the type of disease.
  • Details for the particular types can be found in our separate Fact Sheets.
  • However, in all types, the symptoms reflect brain dysfunction and certain features are common in all types: memory problems, confusion, clumsiness, unsteadiness and jerky movements with progressive disability leading to loss of awareness, loss mobility, loss of speech, incontinence and the need for full nursing care.
  • In sporadic CJD, the progression is typically very rapid with death occurring after a few weeks to months although it can be slower in a small number of cases.
  • In variant CJD, early symptoms are often more psychiatric in nature (such as anxiety or depression) with behavioural changes (such as agitation or social withdrawal). Progression is usually slower than that in sporadic CJD, with the later appearance of unsteadiness, incoordination and other clearly neurological problems, resulting in death generally after 1-2 years.