CJD
What is CJD?
Creutzfeldt-Jakob disease (CJD) is a rare and fatal human disease of the brain and nervous system. It is one of a family of related diseases found in many animal species, called Transmissible Spongiform Encephalopathies (TSEs). These include scrapie in sheep and BSE in cattle. CJD, the disease in humans, can take one of four forms:
- Genetic: in which an abnormal version gene is inherited, causing disease. This is very rare and only a handful of cases would be seen in the UK each year.
- Iatrogenic: whereby CJD has been accidentally transmitted during surgical or medical procedures. This is relatively rare. Most cases have resulted from treating children with human growth hormone though two cases may have arisen through blood transfusion. Measures have been taken to help prevent this happening in the future.
- Sporadic: this is the most common form of CJD. It affects approximately 60 people in the UK each year, usually in later life. Sporadic CJD occurs at a similar level in all countries throughout the world and is not thought to be linked to BSE.
- Variant (vCJD): first discovered in 1996, vCJD is thought to have originated in humans through the consumption of BSE-infected cattle. The average age of onset is 27, which is much younger than the typical age for sporadic CJD. The disease also lasts longer in vCJD patients. By mid 2006, 156 people in the UK had definitely or probably died from vCJD.
What causes CJD?
The cause of CJD is uncertain and still being debated among scientists. It is thought to be most likely to arise from a change in shape in a normal brain protein called prion protein, PrP. The abnormally-folded protein, PrPSc, is then thought to prompt further PrP molecules to change shape. This process leads to the destruction of brain cells, causing gaps in brain tissue which give it a sponge-like appearance under a microscope.
There is currently no cure for any form of CJD.
CJD can be present in the body for many years without causing symptoms, However, once the first symptoms occur patients usually die within twelve months. A minority of patients may live for up to two years, or, in relatively rare cases, for many years.
Early symptoms are often like those of depression, such as mood swings, memory lapses, social withdrawal and lack of interest. In sporadic CJD, there is a rapid progression to dementia and loss of movement control. Later symptoms include blurred vision or blindness, hallucinations, jerky movements and incontinence. Most patients die within a few months of diagnosis though some have survived for several years.
In vCJD, the early symptoms differ in some ways from those of sporadic CJD. Patients can often be initially misdiagnosed with a psychiatric illness, and it may not be apparent that the patient is suffering from a disease of the nervous system until physical symptoms appear a month or two later. vCJD progresses more slowly, with neurological symptoms developing over the course of 12 months on average, with most patients surviving for at least a year.
A snapshot of MRC research into CJD
In 1998, the MRC established the MRC Prion Unit, directed by Professor John Collinge, at the Institute of Neurology in London. The unit has a multidisciplinary approach to research on prion disease, ranging from basic to clinical science. Here are some examples of current projects:
- Studies on the Kuru tribe in Papua New Guinea have yielded valuable information about the disease. In the past, the tribe engaged in rituals involving consumption of the brains of dead relatives. This led to the propagation of prion disease within the tribe, with incubation periods of up to 50 years or more now being identified by researchers.
- A genetics programme which aims to develop understanding of how an individual’s genetic make-up influences their susceptibility to infection and subsequent disease progression.
- A major drug discovery programme in collaboration with GlaxoSmithKline, funded by the Department of Health, the aim of which is to identify molecules which might be employed to treat and or prevent disease in the future.
- Professor Nigel Hooper at the University of Leeds is investigating the biochemical processes involved in prion disease and their relationship and similarity with those of other dementias, such as Alzheimer’s disease. Click here to find out more.
- Professor Jean Manson and colleagues at the Roslin Institute in Edinburgh have carried out studies looking at how TSEs transmit across species and the implications that this may have for human-to-human transmission through contaminated surgical instruments. Click here to find out more.
- Report from Professor Ian Bone – Intraventricular Pentosan Polysulphate in Human prion disease. A study of experience in the United Kingdom.
Useful Links
CJD Support Network UK charity set up by families of people who have died of CJD, offering support, information and care for CJD patients and their carers.
NHS Direct: CJD Provides information about symptoms, causes, diagnosis and treatment of CJD.
Food Standards Agency: BSE Information about eating infected food (especially beef) as a cause of CJD, including the strict controls now in place in the UK to prevent this.
