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CJD Support Network

What is CJD?

Learn more about Creutzfeldt-Jakob disease (CJD) and prion diseases. Head to our Real Stories page to read about the lived experience of people with a personal connection to CJD.

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What is CJD?

CJD is one of a group of diseases called prion diseases, it affects 1 – 2 people per million of the population per year. The lifetime risk of CJD is around 1 in 5,000.

There are three types of prion disease:

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 prion diseases

include genetic CJD, Gerstmann Sträussler Scheinker disease (GSS) and Fatal Familial Insomnia (FFI) and account for around 10-15 percent of cases. They are inherited forms of prion disease which tend to have a younger onset and a longer time course than sporadic CJD. 

Acquired CJD

includes iatrogenic CJD and variant CJD. Iatrogenic CJD occurs through contamination with infected tissue via medical procedures, for example, the use of human growth hormone, blood transfusion, or surgical instruments. 

Variant CJD was caused by exposure to bovine spongiform encephalopathy (BSE) and typically affects younger people. It has a relatively long time course – an average of 14 months from onset of symptoms.

Symptoms of CJD and prion diseases

The precise symptoms and clinical time course of CJD and prion diseases vary according to the type of disease. Details for the particular types can be found in our separate Fact Sheets.

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 of mobility, loss of speech, incontinence, and the need for full nursing care.