• Bookmark and Share

Creutzfeldt-Jakob disease

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

Early symptoms include personality changes and memory problems. But other symptoms develop soon, such as loss of co-ordination, blindness, coma and eventually death sometimes in as little as six months.

Current treatments are limited to reducing symptoms and making patients more comfortable.

  • About CJD
  • Symptoms
  • Causes
  • Diagnosis
  • Treatment
  • Further information
  • Sources

About CJD

There are three main forms of Creutzfeldt-Jakob disease (CJD).

Sporadic (or classical) CJD

Sporadic CJD is a naturally occurring condition that affects around one in a million people each year. It's found all over the world. The cause of sporadic CJD isn't known, but researchers think it may occur when the way in which certain proteins in the brain fold changes by chance.

CJD can't be caught from another person or animal. It isn't related to diet or inherited. Symptoms tend to appear suddenly between the ages of 55 and 75. Death occurs about six months later. It is still the most common form of CJD.

Inherited (or familial) CJD

Inherited CJD is caused by a faulty gene, and is passed down from parents to their children. It's very rare; there are only a few deaths from it in the UK every 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 the faulty gene from just one parent. Symptoms are similar to those of sporadic CJD. But they appear at a younger age and have a longer time course than sporadic CJD.

Acquired CJD

CJD can also occur in two other ways:

  • following accidental infection during medical procedures - known as iatrogenic CJD
  • after eating infected beef products - known as variant CJD (vCJD).

Iatrogenic CJD is very rare. Although CJD can't be caught through normal day-to-day contact, it can be transmitted through contact with the brain or spinal cord, or the cerebrospinal fluid that surrounds these tissues.

In the past, CJD has been passed on through surgical transplants of the dura mater (the membrane that covers the brain) or the transparent tissue that covers the front of eye (cornea). It has also been passed on through injections of hormones and through surgical equipment that hasn't been properly sterilised.

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) has similar symptoms to other forms of the disease. However, it occurs earlier, at an average age of 28. It also seems to cause more personality changes at first; other changes, such as memory or movement problems, are seen later. The time between first symptoms and death is around 12 months.

As of January 2008, there have been 163 cases of definite or suspected variant CJD in the UK.

Symptoms

CJD causes dementia that progresses very rapidly. Early symptoms of the disease include:

  • changes in your personality, including depression and loss of interest
  • problems with vision and hallucinations (seeing things that aren't there)
  • memory problems
  • impaired coordination

These symptoms are quickly followed by movement disorders, especially poor balance and jerkiness. As the disease continues, people often become blind, lose their memory and lose the ability to talk. Eventually, they go into a coma and are likely to die of infections such as pneumonia.

Causes

All forms of CJD are caused by faulty proteins in the brain. The proteins, called prions, are the same as harmless proteins that occur naturally on the surface of the brain cells, but are abnormally folded (misfolded).

Although it isn't fully understood how, the misfolded protein turns any of the normal protein molecules it meets into the harmful form. Misfolded protein molecules then spread through the brain, coming together to form clumps. These bundles of twisted protein disrupt the brain cells, and eventually leave large holes in the brain tissue, giving the brain a spongy appearance.

CJD is one type of a disease called transmissible spongiform encephalopathy or a prion disease. Types of this include kuru (which used to be found in a tribe in Papua New Guinea) and the sheep disease scrapie.

Bovine spongiform encephalopathy (BSE)

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

The risk of passing on BSE from cattle into the human food chain was reduced by measures introduced in the UK in 1989. These included the removal of high-risk materials, such as the spinal cord, from carcasses before they were processed into food, and the exclusion of animals over 30 months from the human food chain. Bonemeal was removed from animal feed. Following a recent European union directive, 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 is now rapidly declining in the UK.

Variant CJD incubation time

There are now controls to eliminate the risk of transmission from animals to humans. However, the exact number of people infected with vCJD isn't known. The main reason is that scientists aren't sure how long after infection with the harmful prion symptoms appear (the incubation time). It could be decades. Consequently, expert estimates of how many more people are yet to develop the disease range from just tens to thousands of people.

Diagnosis

CJD can only be diagnosed definitively by a post-mortem examination of the brain. However, there are several clues that help diagnosis before death. These include the disease's unusually fast speed of progression and clues from brain scans, such as magnetic resonance imaging (MRI).

CJD, along with some other brain diseases, causes increases in a protein called 14-3-3. This protein can be detected in a blood sample. The prion protein can often be seen in a sample (biopsy) of tonsil tissue as well.

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

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

Treatment

At the moment there is no cure for CJD. Treatments are available to reduce some symptoms, such as controlling the pain, and reducing jerky movements. Many drugs have been tested for their ability to slow the progress of the disease. However, none have been shown to be useful. Recent research in the USA has found that some drugs which slow prion protein production in the laboratory. These are being investigated in clinical trials. Another drug appears to prolong the incubation period of prion diseases in animals. This is also being evaluated.

At present, care consists of managing the specific problems faced by patients with CJD. Speech therapy and occupational therapy may be of help. The support of district nurses and social services is often invaluable for people with CJD and their carers.

As the disease progresses, people with CJD will eventually need full nursing care either at home or in a hospice or hospital.

Further information

CJD Support Network

Sources

  • What is vcjd? The Department of Health. www.dh.gov.uk, accessed 01 March 2007
  • The different types of cjd. The national CJD surveillance unit. www.cjd.ed.ac.uk, accessed 5 March 2007
  • CJD: Clinical features. The national CJD Surveillance Unit. www.cjd.ed.ac.uk, accessed 5 March 2007
  • CJD Statistics. The national CJD Surveillance Unit. www.cjd.ed.ac.uk, accessed 5 March 2007
  • About BSE and other TSEs. Food Standards Agency. www.food.gov.uk, accessed 5 March 2007
  • Iatrogenic vCJD from Surgical Instruments BMJ. www.bmj.com, accessed 5 March 2007
  • Investigations Undertaken in Possible CJD Cases. The national CJD Surveillance Unit. www.cjd.ed.ac.uk, accessed 5 March 2007
  • Current Key Issues. Department of Health. www.dh.gov.uk, accessed 01 March 2007