BSE

Creutzfeldt-Jakob disease (CJD) is a rare and fatal condition that affects the brain. It causes brain damage that worsens over time.

Symptoms of CJD include:

• loss of intellect and memory
• change in personality
• loss of balance and co-ordination
• slurred speech
• vision problems and blindness
• abnormal jerking movements
• progressive loss of brain function and mobility

Most people with CJD will die within a year of the symptoms starting, usually from infection. This is because the immobility caused by CJD can make people with the condition vulnerable to infection.

Read more about the symptoms of Creutzfeldt-Jakob disease and diagnosing Creutzfeldt-Jakob disease.

What causes CJD?

CJD appears to be caused by an abnormal infectious protein called a prion. These prions accumulate at high levels in the brain and cause irreversible damage to nerve cells, causing the symptoms described above.

While the abnormal prions are technically infectious, they are very different to viruses and bacteria. For example, prions are not destroyed by the extremes of heat and radiation used to kill bacteria and viruses, and antibiotics or antiviral medicines have no effect on them.

Read more about the causes of Creutzfeldt-Jakob disease.

Types of CJD

There are four main types of CJD.

Sporadic CJD

Sporadic CJD is the most common type of CJD.

The precise cause of spradic CJD is unclear, but it has been suggested that in some people a normal brain protein undergoes an abnormal change (misfolding) and turns into a prion.

Most cases of sporadic CJD occur in older adults aged between 45 and 75 years, with the average age of symptoms developing being around 60-65 years.

Despite being the most common type of CJD, sporadic CJD is still very rare, affecting only 1-2 in every million people each year in the UK.

There were 83 recorded deaths from sporadic CJD in the UK during 2012.

Variant CJD

Variant CJD is likely to be caused by consuming meat from a cow that has been infected with a similar prion disease called bovine spongiform encephalopathy (BSE) - also known as 'mad cow disease'.

Since the link between variant CJD and BSE was discovered in 1996, strict controls have proved extremely effective in preventing meat from infected cattle from entering the food chain (see preventing Creutzfeldt-Jakob disease for more information).

However, the average time it takes for the symptoms of variant CJD to occur after initial infection (the incubation period) is still unclear. The incubation period could be very long (over 10 years) in some people, so people who were exposed to infected meat before the food controls were introduced can still develop variant CJD.

The prion that causes variant CJD can also be transmitted by blood transfusion, although this has only happened four times in the UK.

There have been 177 recorded cases of variant CJD in the UK to date and there were no recorded deaths from the condition in the UK during 2012.

Familial or inherited CJD

Familial CJD is a very rare genetic condition where one of the genes a person inherits from their parent (the prion protein gene) carries a mutation that causes the formation of prions in their brain during adulthood, triggering the symptoms of CJD. It affects about 1 in every 9 million people in the UK.

The symptoms of familial CJD usually first develop in people aged in their early 50s.

There were ten deaths from familial CJD and similar inherited prion diseases in the UK during 2012.

Iatrogenic CJD

Iatrogenic CJD is where the infection is accidentally spread from someone with CJD through medical or surgical treatment.

For example, a common cause of iatrogenic CJD in the past was growth hormone treatment using human pituitary growth hormones extracted from deceased individuals, some of whom were infected with CJD. Synthetic versions of growth hormones are now used, so this is no longer a risk.

Cases of iatrogenic CJD can also occur if instruments used during brain surgery on a person with CJD are not properly cleaned between each surgical procedure before re-use on another person.

Increased awareness of these risks, however, means iatrogenic CJD is now very rare. There were five deaths from iatrogenic CJD in the UK during 2012.

How CJD is treated

There is currently no cure for CJD, so treatment involves helping to relieve symptoms and making the affected person feel as comfortable as possible.

This can include using medication such as antidepressants to improve anxiety and depression, and painkillers to relieve pain. Assistance with feeding and nursing care for bedridden patients may also be needed.

Read more about treating Creutzfeldt-Jakob disease.