Creutzfeldt-Jakob disease (CJD) is caused by an abnormally shaped protein called a prion infecting the brain.
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What is Creutzfeldt-Jakob disease (CJD)?
Creutzfeldt–Jakob disease (CJD) is caused by an abnormally shaped protein infecting the brain. This protein is called a ‘prion’. It is not known what causes prions to build up in the brain, but in most cases CJD is not thought to be inherited or transmitted from person to person.
CJD affects about 1 in every million people each year. The most common type is sporadic CJD. This normally affects people aged over 40. If a person has sporadic CJD, their symptoms of dementia usually progress very quickly (within just a few weeks or months). Early symptoms include minor memory loss, mood changes and apathy.
Within weeks the person may become clumsy and confused. They may also become unsteady when they walk and have slow or slurred speech. Their symptoms are likely to progress to:
- jerky movements
- stiff limbs
- loss of the ability to move or speak.
By this stage the person is unlikely to be aware of their surroundings or disabilities. There is currently no cure for CJD, although some of the physical symptoms can be managed better with drugs, such as clonazepam for stiff limbs and seizures.
For sporadic CJD to be diagnosed, a person will have a medical procedure known as a lumbar puncture. In this, a thin needle is inserted between two bones in the lower back to remove some spinal cord fluid and look for specific changes in it. This normally involves a referral to the National CJD Research & Surveillance Unit. See Rarer types of dementia - other resources.
A form of CJD called ‘new variant CJD’ was identified more recently. It may be caused by eating meat from cattle that have bovine spongiform encephalopathy (BSE). This is why new variant CJD is also known as ‘mad cow disease’. In the past, it caused a small number of people to develop new variant CJD. It is now very rare for a person in the UK to develop this condition.