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Creutzfeldt-Jakob Disease (CJD)

Content provided by the Faculty of the Harvard Medical School

What Is It?

Creutzfeldt-Jakob disease (CJD) is a rare, fatal brain disorder associated with a misshapen protein in the brain, known as a prion. Although prion-associated diseases are not well understood, scientists theorize that prions cause damage by causing healthy proteins in the brain to take the prion shape, so these too become damaging particles. This slow chain reaction of damaged proteins occurs over many years and results in brain damage.

When symptoms eventually appear, CJD causes rapidly progressive dementia (mental decline) and involuntary jerking muscle movements called myoclonus. About 90% of people with CJD die within 1 year of diagnosis.

CJD is considered an infectious illness. However, prions do not move easily from one person to another. Most cases of CJD are not caused by exposure to another person with the disease but by an accidental mutation in brain cell DNA that allows a prion particle to be formed. This mutation can be sporadic (occurring for the first time in a family, without a family history of the same gene mutation and disease) or hereditary (passed down from parent to child). Most cases of CJD are sporadic. Between 5% and 15% are caused by inheritance of the gene mutation that encodes the prion protein. Jewish people born in Czechoslovakia, Chile and Libya have a higher-than-average number of inherited cases of CJD. Because the effects occur very slowly, inherited CJD does not cause symptoms until adulthood.

A type of CJD called "variant CJD" shows somewhat slower progression of brain injury and more psychiatric symptoms, and it tends to affect younger people. This type of CJD has been linked to eating beef from cattle infected with bovine spongiform encephalopathy (BSE), also called "mad cow disease." Beef products from infected cows can contain prion particles, which is why they can pass infection to people. This small outbreak of variant CJD was described in the United Kingdom and peaked in 1999. Since then, changes in beef farming and processing practices have helped to limit the number of new cases. All but 11 cases of variant CJD occurred in the United Kingdom. Seven cases have been diagnosed in France, and one case has been diagnosed in Italy. Three other countries (Canada, Ireland and the United States) have each had one case, all in travelers who had been in the United Kingdom and had eaten beef there during the outbreak years.

It is extremely uncommon for this disease to spread from one person to another, but in recent years, three people have acquired variant CJD after receiving blood transfusions. These cases prompted blood banks to start using extra precautions, such as preventing people in the United States from donating blood if they lived in a country where BSE is common for more than 3 months. It is possible to spread CJD (and presumably variant CJD) during medical procedures because it can spread on contaminated equipment such as surgical instruments and brain electrodes. Also, the illness can be spread by contaminated tissue, such as corneas that are used for transplant, and injections of pituitary gland extracts containing human growth hormone or injections of human gonadotropin hormones, which have been used to treat infertility. Synthetic hormones do not pose any risk of CJD.


CJD does not cause any symptoms at first. The first symptoms to appear include slow thinking, difficulty concentrating, impaired judgment and memory loss. These types of symptoms can overlap with some other neurological problems, such as Alzheimer's disease or Huntington's disease. Soon after these symptoms appear, they lead to severe, progressive dementia (mental decline) associated with self-neglect, apathy or irritability and prominent muscle spasms. Patients become completely bedridden as brain injury worsens, and eventually lapse into coma. Comatose patients may die as a result of infection associated with being immobile, such as pneumonia.


Laboratory tests cannot detect CJD but may be used to check for other, treatable conditions. Cerebral spinal fluid may be tested for the presence of a protein associated with CJD, but this protein is not the prion that causes disease, and it also is present in people with other types of dementia. This makes it an imperfect test.

Brain imaging tests, including computed tomography (CT) and magnetic resonance imaging (MRI) scans may be done to look for atrophied (shrunken) brain tissue. An electroencephalogram (EEG) records the brain's electrical pattern and may support the diagnosis because CJD causes a particular pattern of electrical activity in 75% to 95% of people with this disease. These EEG changes are not usually present at very early or very late stages of the disease.

A small sample of brain tissue may be taken to be analyzed in a laboratory. In CJD, brain tissue contains small round holes called spongiform changes, meaning the tissue resembles a sponge. However, a brain biopsy could hurt the patient, and it would only be done if there were a possibility the patient may have another disorder that could be treated.

Expected Duration

Ninety percent to 95% of people with CJD die within 3 to 12 months after symptoms start. A few people with the disease survive more than 2 years. Mental deterioration becomes more pronounced as the disease progresses, leading to blindness, weakness in the extremities and coma. In variant CJD caused by eating infected meat, the disease may progress more slowly.


Health care professionals can minimize the risk of transferring prions from patients with CJD by handling their fluids and tissues with extreme caution and by using special sterilization methods to disinfect equipment. People donating tissues, such as corneas for transplantation, should be investigated to determine whether they have CJD.

New precautions have been taken by the beef farming and beef processing industry. These precautions have helped to make the risk of infection from eating beef exceedingly small. Some of the most important changes have been government regulations, including a requirement in Europe that animals used for food be no more than 30 months old, and a requirement that a cow's brain, spinal cord and some muscles from these body areas should be discarded instead of being processed into human or animal food.

Although the risk of acquiring variant CJD is extremely low, travelers to the United Kingdom or Europe may decide to avoid beef or to eat steak rather than products such as sausage or burgers, since ground beef is more likely to be contaminated. Milk and dairy products have never been shown to spread variant CJD infection.

Blood banks have put additional restrictions on blood donors. Blood banks in the United States now turn away blood donations from people who have lived in the United Kingdom for three months or longer from 1980 through 1996.


CJD cannot be cured, but some of the symptoms can be treated. Narcotics may be used to relieve pain, and anticonvulsant drugs, such as clonazepam (Klonopin) and valproic acid (Depacon, Depakene, Depakote), may be used for muscle spasms. Research studies are looking into other drugs that may be helpful.

When To Call A Professional

Seek medical help for signs of dementia such as sudden or gradual changes in memory, thinking skills, mood or behavior and for alterations in vision or movement ability.


The disease is fatal, with the majority of deaths occurring within 3 to 12 months of illness.

Additional Info

National Institute of Neurological Disorders and Stroke Brain Resources and Information Network (BRAIN) P.O. Box 5801 Bethesda, MD 20824 Toll-Free: 1-800-352-9424 TTY: 301-468-5981

Creutzfeldt-Jakob Disease Foundation, Inc. P.O. Box 5312 Akron, Ohio 44334 Toll-Free: 1-800-659-1991 E-mail:

Centers for Disease Control and Prevention (CDCP) U.S. Department of Health and Human Services 1600 Clifton Road Atlanta, GA 30333 Toll-Free: 1-800-311-3435 E-mail:

Last Annual Review Date: 2008-03-10T00:00:00-06:00 Copyright: Medical content reviewed by the Faculty of the Harvard Medical School. Copyright © 2010 by Harvard University. All rights reserved. Used with permission of StayWell.

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