Creutzfeldt-Jakob Disease (CJD)


What Is It?

Creutzfeldt-Jakob disease (CJD) is a rare, fatal brain disorder associated with the presence of 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 appear, CJD causes rapidly progressive dementia (mental decline) and involuntary jerking muscle movements called myoclonus. About 90 percent of those affected die within one year of diagnosis.

Because contamination by prion particles can spread this disease, it 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 rather 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 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 percent and 15 percent are caused by inheritance of the gene mutation that encodes the prion protein. Czechoslovakian-, Chilean- and Libyan-born Jews 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.

It is extremely uncommon for this disease to spread from one person to another, but during medical procedures, it can spread on contaminated equipment, such as surgical instruments and brain electrodes, or contaminated tissue, such as corneal transplants, natural human growth hormone and human gonadotropins for treatment of infertility. In Britain, a small number of cases of CJD have recently been linked to the consumption of beef from cattle infected with bovine spongiform encephalopathy, or mad cow disease.


CJD does not cause any symptoms at first. The first symptoms to appear include slow thinking, difficulty concentrating, impaired judgment, memory loss, personality and behavioral changes, and difficulties with coordination and vision. These symptoms rapidly give way to increasing mental deficits leading to severe, progressive dementia (mental decline) associated with self-neglect, apathy or irritability, and prominent muscle spasms (myoclonus). As the disease progresses, seizures commonly occur. Symptoms continue to worsen until both mental and physical functions are lost; patients are completely bedridden, and eventually lapse into coma. Comatose patients may die as a result of infection associated with being immobile, such as pneumonia.


Laboratory tests are ineffective in detecting CJD but may be used to rule out 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.

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 may be done. This test can show characteristic changes in electrical brainwave patterns in 75 percent to 95 percent of people with this disease, but these 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.

Expected Duration

Ninety percent to 95 percent of people with CJD die within three to 12 months after symptoms start. A few people with the disease survive more than two years. Mental deterioration becomes more pronounced as the disease progresses, leading to blindness, weakness in the extremities and coma. When CJD occurs in people who have eaten infected meat, the disease may progress more slowly.


Health-care providers can minimize the risk of transferring prions from patients with CJD by handling their fluids and tissues with extreme caution, and using special sterilization methods to disinfect equipment. People donating tissues, such as corneas for transplantation, should be investigated to determine whether they have CJD. In general, the risk of infection from eating beef is exceedingly small now that cattle are watched more closely for any signs of CJD infection.


CJD cannot be cured, but symptoms can be treated. Opiate drugs 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.

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 three to 12 months of illness.

Johns Hopkins patient information

Last revised:

Diseases and Conditions Center

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.