Creutzfeldt-Jakob disease (CJD)

Published by Bupa's Health Information Team, May 2010.

This factsheet is for people who have Creutzfeldt-Jakob disease, or who would like information about it.

Creutzfeldt-Jakob disease (CJD) is a very rare disease that causes severe brain damage.

About CJD

CJD is a type of disease called transmissible spongiform encephalopathy or a prion disease. It's caused by faulty proteins in your brain. The proteins, called prions, are the same as harmless proteins that occur naturally on the surface of your brain cells, but they are abnormally folded (misfolded).

CJD causes progressive brain damage and is fatal.

Types of CJD

There are four types of CJD.

Sporadic (or classical) CJD
Sporadic CJD is the most common type of CJD. It's a naturally occurring condition, which can't be caught from another person or animal. It isn't inherited or related to your diet.

Symptoms of sporadic CJD tend to appear suddenly between the ages of 55 and 75. Death occurs about six months later. Sporadic CJD is thought to cause between 50 and 60 deaths a year in the UK.

Inherited (also known as genetic or familial) CJD
Inherited CJD is caused by a faulty gene, which is passed down from parents to their children. It's very rare; only a few people die of it in the UK each year.

There are many faulty genes that can cause CJD, most of which are dominant. This means that you can develop the disease if you inherit a faulty gene from just one of your parents. Symptoms appear at a younger age and develop over a longer period of time than those of sporadic CJD.

Iatrogenic CJD
Iatrogenic CJD is CJD that develops after accidental infection during a medical procedure. It's very rare.

In the past, CJD has been passed on through surgical transplants of the dura mater (the membrane that covers your brain) or the cornea (the transparent tissue that covers the front of your eye) of an infected person. It has also been passed on through contaminated injections of human growth hormones and though the use of contaminated surgical equipment. Nowadays, to prevent this happening, transplants aren't taken from infected people, surgical equipment used on people with CJD is never used on other people and growth hormone treatment is made artificially.

Variant CJD
Variant CJD (vCJD) develops after you have eaten infected beef products. Variant CJD used to be called new variant CJD (nvCJD). It was passed from cows with bovine spongiform encephalopathy (BSE or 'mad cow disease') to humans.

Variant CJD (or vCJD) occurs earlier than other types of the disease, at an average age of 28. The time between first symptoms and death is around 14 months.

As of March 2010, there have been 168 deaths from definite or suspected variant CJD in the UK. The exact number of people infected with vCJD isn't known. The main reason for this is that scientists aren't sure how long after infection with the harmful prion symptoms appear (the incubation time). It could be decades. Expert estimates of how many more people are yet to develop the disease range from just tens to thousands of people.

Symptoms of CJD

The symptoms of CJD vary depending on which type of the disease you have. However, many symptoms are common across all types.

Early symptoms of the disease include changes in personality, depression and loss of interest in life.

Symptoms will then get worse. For people with sporadic CJD, confusion and loss of memory are common. In variant CJD, the depression gets worse and other symptoms such as anxiety, delusions and hallucinations set in.

After a while, other symptoms will include:

• loss of co-ordination and balance
• problems with movement, especially poor balance and jerkiness
• problems seeing or hearing
• memory and speech loss
• muscle paralysis
• incontinence

Eventually, people with CJD go into a coma and are likely to die of infections such as pneumonia.

Causes of CJD

CJD is caused by faulty proteins in your brain, called prions. Prions are abnormally folded (misfolded). Although it isn't fully understood how, prions cause the normal protein molecules they meet within your brain cells to become misfolded as well. Your brain cells die releasing more prions to infect other brain cells and eventually leaving large holes in your brain tissue, giving your brain a spongy appearance.

Bovine spongiform encephalopathy (BSE)

BSE is a prion disease that affects cows and was discovered in 1986. Like other prion diseases, it causes progressive brain damage. Scientists aren't sure where BSE came from. However, once the disease appeared in cows, it spread rapidly through British cattle. This is because it was previously common practice to use cow tissue to make bonemeal, which was then fed to other cattle.

Variant CJD was transmitted to humans from cows infected with BSE. The risk of BSE passing from cattle to humans was reduced by measures introduced in the UK in 1989. These measures included the removal of high-risk materials, such as the spinal cord, from carcasses before they were processed into food, and animals over 30 months not being used for human food. Bonemeal was removed from animal feed. Mechanically recovered meat from around the backbone of cows, sheep and goats is now also banned. Because of these measures, the number of cows with BSE has rapidly declined in the UK.

There are still controls in place to stop the risk of transmission from cows to humans. Cattle over a certain age must be tested for BSE before being used for human food.

Diagnosis of CJD

CJD can only be properly diagnosed by examining your brain tissue. A biopsy (a sample of your brain tissue) can be taken and sent for testing. However, this is very rarely carried out while you're alive because it can cause a brain injury or seizure.

There are several clues that can help your doctor to make a diagnosis, including the disease's unusually fast progression.

Tests you may have include the following.

• MRI scan, which can show any abnormalities particular to CJD.
• EEG (electroencephalogram), which measures your brain's electrical activity. Sporadic CJD causes a distinctive pattern.
• Lumbar puncture to take a sample of the fluid surrounding your brain and spinal column to check for a protein called 14-3-3. This protein is detected in all people with sporadic CJD and half of people with variant CJD.
• Tonsil biopsy to remove a sample of your tonsil tissue. The prion protein can often be seen in a sample of tonsil tissue but only if you have variant CJD.

You may have genetic testing if your doctor suspects that you have the inherited form of CJD. This is to increase the certainty of your diagnosis, as you would usually have a family history of the disease.

Iatrogenic CJD is usually diagnosed on the basis of your medical history. Those at risk include people who received hormones derived from humans before 1992 or dura mater transplant grafts before 1985.

Treatment of CJD

At the moment there is no cure for CJD. However, treatments are available to reduce some of the symptoms, such as controlling the pain, and reducing jerky movements, while antidepressants are prescribed for depression and anxiety.

Once you're diagnosed with CJD, you will be assigned a keyworker such as a social worker who can liaise on your behalf between your local health authority and the National CJD Care team.

Your keyworker will help set up support to manage your symptoms. This may involve speech therapy, occupational therapy to help adapt your home to your needs and seeing a dietitian or incontinence adviser. The support of district nurses and social services is often invaluable for people with CJD and their carers.

As the disease progresses, you and your family will need more and more support, eventually leading to full-time nursing care either at home or in a hospice or hospital.

For answers to frequently asked questions on this topic, see Common questions.

For sources and links to further information, see Resources.