Creutzfeldt-Jakob disease (CJD) is a rapidly progressing disease of the nervous system, which destroys brain tissue (neuro-degeneration). There are several forms of the disease, the most common of which is sporadic CJD (also known as ‘classical CJD’), which has no identifiable cause as yet, and which affects mostly middle-aged or elderly people.

All forms of CJD are rare and fatal. In the UK in 2002 there were 147 suspected cases of CJD, a similar rate to elsewhere in the world. About 85% of CJD cases are sporadic, the rest are either inherited (genetic CJD), or in very rare cases accidentally transmitted by medical procedures (iatrogenic CJD).

A new type of CJD, new variant CJD, now referred to simply as variant CJD (vCJD) first identified in 1996. It affects mostly younger adults (average age 27), and has different clinical and pathological characteristics. Variant CJD accounted for approximately 25% of all CJD deaths in 2002.

There is clear evidence that variant CJD is caused by the same strain of infectionthat causes what is known as ‘mad cow disease’ (bovine spongiform encephalopathy or BSE). The BSE Enquiry in 2000 concluded that BSE agent was spread through compound cattle feed, and had entered the human food chain. The evidence suggests that the most likely explanation for variant CJD cases is exposure to the BSE agent (but there is no known link to sporadic CJD).

All forms of CJD can be present in a person for long periods (often over 20 years) during which there are no symptoms, but the process of disease is present. The duration of the illness before death varies from a matter of weeks (typical of sporadic CJD) to 3-12 months (typical of variant CJD). However, there have been exceptions in both types.

Causes

The disease occurs when body tissuefrom an infected animal or person passes into the body. It is not passed by normal social contact. CJD is an infection with an agent called a prion, an abnormal form of a protein called PrP.

The function of a normal PrP protein is unknown, but is thought to be necessary in some way for the brain to function normally. When prions become active brain cells become mutated and start to die

Treatment

There is no proven therapy or cure for any of the forms of CJD. Treatment is based entirely upon reducing symptoms through the use of drugs, and trying to keep the person as comfortable as possible.

Symptoms

The initial symptoms of variant CJD are similar to those of depression; mood swings, memory lapses, fatigue, irritability, sleep problems, withdrawal from social activities, lack of interest in life, and neglect of personal hygiene. It may not be clear that the individual has a serious disease of the nervous system, until several months after the start, when these early signs are rapidly joined by more physical symptoms of a deterioration of the nervous system.

In contrast, the early symptoms of sporadic CJD are more clearly those of a physical illness of the nervous system that gets very rapidly more severe, but which is also accompanied by behavioural problems such as those found in dementia.

 Other symptoms include:

• increasing loss of memory,
• reasoning and understanding,
• loss of balance,
• paralysis,
• loss of sensation,
• speech disorder,
• disorientation,
• clumsiness,
• tremor,
• twitching,
• and, other signs of progressive destruction of brain function occur.