What is Prion Disease? from the Alzheimer's Society, U.K.

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What is Creutzfeldt-Jakob disease (CJD)?

Creutzfeldt-Jakob disease (CJD) is the best known of a group of diseases called prion disease, which affect a form of protein found in the central nervous system and cause dementia. It was first reported by two German doctors (Creutzfeldt and Jakob) in 1920, although it has been well recognised in animals for centuries. This factsheet provides an overview of the symptoms and different types of CJD.

What is prion disease?

Prions are proteins found in the central nervous system of all mammals. Their function is unknown. In prion disease, these proteins fold abnormally, forming clusters in the brain. When the brain cells die, they cause spongiosis (holes in the brain matter, which makes the brain look like sponge when viewed under the microscope). This results in neurological dysfunction, or dementia.

Prion disease is extremely rare and accounts for less than 0.1 per cent of all cases of dementia. CJD makes up eighty per cent of instances of prion disease, usually in people aged 60-65 years old. There are also two extremely rare inherited prion diseases: Gerstmann-Straussler-Scheinker disease (GSS) and fatal familial insomnia (FFI).

What are the symptoms of CJD?

* Early symptoms include minor lapses of memory, mood changes and loss of interest.
* Within weeks, an infected person may complain of clumsiness and feeling muddled, become unsteady in walking, and exhibit slow or slurred speech.
* The symptoms progress to jerky movements, shakiness, stiffness of limbs, incontinence and the loss of the ability to move or speak. By this stage, the person is unlikely to be aware of their surroundings or disabilities. Eventually the person will need full nursing care.

There may be many years between a person being infected, or having the first misfolded prion problem, and the development of symptoms.

People affected by CJD usually die within six months of early symptoms − often from pneumonia. In a minority of patients, the disease may take two years to run its course. Very rarely, the disease can last for many years.

There is no evidence that people with CJD are in pain, provided they are well nursed and comfortable. Drugs can alleviate some symptoms, such as shakiness.

Types of CJD

There are four forms of CJD − sporadic, familial, iatrogenic and variant.

Sporadic CJD

The cause of sporadic CJD (also called 'classical CJD') remains unknown. It is marked by rapid onset of dementia, and mainly affects those over the age of 50. The course of the disease is usually measured in months.

Familial CJD

This is an inherited form of CJD. Those affected appear to be genetically predisposed to produce the abnormal form of prion proteins. People usually develop familial CJD at an earlier age than the sporadic form (20-60 years of age) and the course of the illness is usually longer, at between two and ten years.

Iatrogenic CJD

This form of CJD arises from contamination with the tissue or blood of an infected person − usually as a result of a medical procedure such as corneal transplant, a graft, or the use of growth hormone. A few people have been infected through the use of neurosurgical instruments.

Today, no transplants are taken from infected people and growth hormone is made artificially. Surgical instruments used on people with CJD are never used on other patients because prions cannot be eradicated by normal sterilisation procedures.

Variant CJD

In 1996, a new type of CJD was reported. Variant CJD appears to affect younger people than the other forms of the disease, with an average age of death of 29 years. (However, one case of a 74-year-old man with variant CJD has been reported.) The average length of illness is 14 months.

There is now evidence that variant CJD is caused by bovine spongiform encephalopathy (BSE) - a form of prion disease affecting cattle. Prion diseases have been found in several other animal species, including sheep (scrapie), deer, cats, mink and zoo animals. The consumption of infected beef products appears to have led to the development of BSE in humans.

Since 1989, action has been taken to remove those parts of cattle where the greatest concentrations of infective agent are found, including brains and spinal cords, from the human food chain.

There is some evidence that the number of deaths from variant CJD has reached a peak and is now in decline. However, there is currently no firm scientific basis for predicting future numbers of cases of variant CJD, and there could be more than one peak to the epidemic. One problem is that the length of the incubation period for the disease remains uncertain. Prions may exist in the body for many years before symptoms begin.

Diagnosis

Initially, someone showing symptoms similar to those described above should go to their GP. If the symptoms give cause for concern, the GP will refer them to a neurologist. The neurologist will investigate a range of causes, including Alzheimer's disease and vascular dementia (see Factsheets 401, What is Alzheimer's disease? and 402, What is vascular dementia?). If no immediate underlying cause is obvious, the neurologist may conclude that the patient has a rare neurodegenerative disease, and may refer them to the National Prion Clinic (see 'Useful organisations') for further assessment.

Treatment

There is no proven effective treatment available as yet. However, there are a number of ongoing trials, in the UK and elsewhere, of drugs that may delay the deterioration of prions.

Your local Alzheimer's Society branch will always be willing to talk to you and offer advice and information to support your needs.

For more information, Dementia Catalogue, our specialist dementia information resource, is available on the website at alzheimers.org.uk/dementiacatalogue

Useful organisations

Alzheimer's Society

Devon House
58 St Katharine's Way
London E1W 1JX
T 020 7423 3500
0845 3000 336 (helpline open 8.30am-6.30pm weekdays)
E info@alzheimers.org.uk (general information)
helpline@alzheimers.org.uk (helpline)
W alzheimers.org.uk

The UK's leading care and research charity for people with dementia and those who care for them. The helpline provides information, support, guidance and referrals to other appropriate organisations.

Creutzfeldt-Jakob Disease Support Network

PO Box 346
Market Drayton
Shropshire TF9 4WN
T 01630 673 973
E info@cjdsupport.net
W http://www.cjdsupport.net/

Provides detailed factsheets about the different forms of CJD, as well as advice, information and support for carers and professionals.

Department of Health

Richmond House
79 Whitehall
London SW1A 2NS
T 020 7210 4850 9.00am-5.00pm
020 7210 5025 (textphone)
E use the enquiry form on the website (see below)
W http://www.dh.gov.uk/

The government department responsible for health, social care, and the National Health Service (NHS). Provides a range of information and literature, including on help with NHS costs.

National CJD Surveillance Unit

Western General Hospital
Crewe Road
Edinburgh EH4 2XU
T 0131 537 3073
W http://www.cjd.ed.ac.uk/

Unit at the Western General Hospital, Edinburgh, run by a team of clinical neurologists, neuropathologists and scientists specialising in the investigation of CJD. Provides a range of information about CJD.

National Prion Clinic

Box 98
National Hospital for Neurology and Neurosurgery
Queen Square
London WC1N 3BG
T 020 7405 0755
E help.prion@uclh.org
W http://www.nationalprionclinic.org/

Clinic based at the National Hospital for Neurology and Neurosurgery, Queen Square, London. It provides diagnosis, care and support for patients with, or suspected of having, any form of human prion disease.

Factsheet 427

Last updated: October 2008
Last reviewed: October 2008

Reviewed by: Michele Gorham, Lead Nurse Clinical Specialist Prion Disease, National Prion Clinic