CJD is part of a group of conditions called transmissible spongiform encephalopathies or prion diseases. It's caused by faulty proteins in your brain. The proteins, called prions, are the same as proteins that occur naturally on the surface of your brain cells, but they are abnormally folded (misfolded).
CJD causes progressive brain damage over months or years, eventually leading to death. As yet, there is no cure.
There are four types of CJD.
The exact symptoms of CJD vary depending on which type of the disease you have. However, many symptoms are common across all types. In general, psychiatric symptoms, such as depression, are more likely in people with variant CJD, and cognitive symptoms, such as memory loss and unsteadiness, are more likely with sporadic CJD.
Early symptoms of the disease include:
If you have variant CJD, your depression will probably get worse and you may get other symptoms such as anxiety, delusions and hallucinations.
Later symptoms may include:
Eventually, people with CJD are likely to die of an infection such as pneumonia.
CJD is caused by faulty proteins in your brain, called prions, that are 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 and release more prions to infect other brain cells and eventually this leaves large holes in your brain tissue, which gives your brain its spongy appearance.
The reason for developing faulty prions in your brain depends on which type of CJD you have.
The exact reasons why you may develop sporadic CJD aren't fully understood at present. It isn't inherited or related to your diet.
Inherited CJD is caused by a faulty gene, which you inherit from your parents. 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.
Iatrogenic CJD has been passed on in the past 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) from an infected person. It has also been passed on through contaminated injections of human growth hormones and through the use of contaminated surgical equipment (conventional sterilisation procedures don’t destroy the infectious prion).
At present, 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. See our frequently asked questions for more information.
You can get variant CJD after eating infected beef products. It can be passed from cows with bovine spongiform encephalopathy (BSE or 'mad cow disease') to humans.
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, 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 1988. Because of these, 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.
Variant CJD can also be spread through medical procedures, for example, from person to person through blood transfusions. However, this is very rare.
Your GP will ask about your symptoms and examine you. He or she may also ask you about your medical history.
Your GP may refer you to a neurologist (a doctor who specialises in conditions of the nervous system) for further tests.
CJD can only be properly diagnosed by examining your brain tissue. You may be referred to a neurosurgeon (a doctor who specialises in identifying and surgically treating conditions that affect the nervous system, including the brain) for a brain biopsy. This is when a small sample of tissue is taken and sent to a laboratory for testing. However, this isn’t usually done and your doctor is more likely to make a diagnosis based on your description of your condition – the disease's unusually fast progression may suggest a diagnosis of CJD – and the results of other tests. These may include:
You may have genetic testing if your doctor suspects that you have the inherited type 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 1985 or dura mater transplant grafts before 1992.
There is no cure for CJD. However, there are treatments available to reduce some of the symptoms, such as to control pain and reduce jerky movements. Your doctor can prescribe you antidepressants for depression and anxiety.
Once you're diagnosed with CJD or if your doctor suspects you have the condition, you will be referred to the National CJD Surveillance Unit and assigned a key worker, such as a doctor or nurse. He or she can liaise on your behalf with your local health authority and help you to access health and social services and 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.
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.
It’s very unlikely but there is a very small risk of being infected during an operation with the faulty protein (prion) that causes CJD. However, there are now procedures in place to prevent this and it very rarely happens.
Iatrogenic CJD can develop if you’re accidentally infected during a medical procedure. However, this is very rare.
Iatrogenic CJD can be transmitted if tissue from an infected person comes into contact with your brain, spinal cord, or the cerebrospinal fluid that surrounds these tissues, during a medical procedure. 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). Now, to prevent this happening, transplants aren't taken from infected people.
CJD can also be passed on through the use of contaminated surgical equipment. Surgical instruments are sterilised to clean them of anything that could cause infection, such as viruses and bacteria. However, scientists have shown that the prion that causes CJD can stick to surgical stainless steel and survive standard cleaning methods. There have only been a very small number of reported cases of transmission of CJD in the UK using instruments for brain surgery, and these happened over 30 years ago. Since then decontamination procedures have been improved. Most importantly, surgical equipment used on people with CJD is never used on other people. Therefore, becoming infected with CJD during an operation is extremely unlikely.
No, there is no evidence that CJD can be passed from one person to another by having sex.
The faulty protein (prion) that causes CJD is found in your nervous system, including your brain and spinal cord. It's possible that the disease may be passed on through transplant operations of organs that include these tissues or from blood transfusions. There is also a very small risk that it may be passed on through contamination of surgical instruments but there are now measures in place to prevent this. Other forms of contact aren't a risk. The infection can't be transmitted through shaking hands, sneezing, coughing or having sex.
Not all forms of CJD are linked to eating contaminated meat, so if you're a vegetarian, you can still be affected.
If you have never eaten meat or meat products, it's highly unlikely that you will get variant CJD – the form of the disease that is linked to eating contaminated meat. However, if you used to eat meat in the past, it may be possible that you could get variant CJD as you may be infected but not show symptoms yet (scientists aren't sure how long after you’re infected symptoms appear – it could be decades).
There is a very small risk that you could get one of the other forms of the disease. However, it's important to realise that CJD, in all its forms, is a very rare disease.
Unless CJD runs in your family, or you know that you have been at risk from a medical or surgical procedure, there is only a tiny chance that you may have been affected.