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Creutzfeldt-Jakob Disease (CJD)

(Subacute Spongiform Encephalopathy)

By Pierluigi Gambetti, MD

Creutzfeldt-Jakob disease is a prion disease characterized by progressive deterioration of mental function, leading to dementia, involuntary jerking of muscles (myoclonus), and staggering when walking. A variant form is acquired by eating contaminated beef.

  • The disease usually occurs spontaneously but may result from eating contaminated beef or from inheriting an abnormal gene.

  • At first, most people are confused and have memory problems, then muscles begin to jerk involuntarily and coordination is lost.

  • Most people die within 6 months, although some live for 2 years or more.

  • The diagnosis can usually be confirmed by electrocephalography, analysis of cerebrospinal fluid, and magnetic resonance imaging.

  • There is no cure, but drugs can relieve some of the symptoms.

Creutzfeldt-Jakob disease (CJD) is a prion disease, which develops when a normal protein called cellular prion protein (PrPC) changes into disease-causing prion. Prions slowly accumulate in the brain and usually cause tiny bubbles to form in brain cells, which gradually die. When enough brain cells malfunction or die, symptoms develop, followed by the person's death.

CJD may

  • Occur spontaneously (called sporadic CJD)

  • Occur in families (called familial CJD)

  • Be acquired

Sporadic CJD , the most common form, affects about 1 in a million people each year throughout the world. It accounts for about 85% of cases. It usually affects people over 40 years old, usually around age 60. For this form, no cause is known.

Familial CJD results from a mutation in the gene for PrPC, which causes normal PrPCto change shape (misfold) and become disease-causing prion. It accounts for 5 to 15% of cases. Familial CJD is often inherited and usually starts at an earlier age and lasts longer than sporadic CJD.

Acquired CJD can result from

  • Eating contaminated beef (called variant CJD)

  • Having had certain medical procedures (called iatrogenic CJD)

CJD has never been reported to be transmitted through casual or even intimate contact with people who have the disease.

Variant CJD

Variant CJD (vCJD) is acquired by eating beef or beef products from cattle who have bovine spongiform encephalopathy (mad cow disease).

vCJD usually begins around age 30 or younger, in contrast to sporadic CJD, which usually begins around age 60.

As of February 2015, the following number of cases of vCJD have occurred:

  • Worldwide: 229

  • United Kingdom: 177

  • France: 27

  • Elsewhere: 25

Only three people acquired vCJD from transfusion of contaminated blood.

Considering that for years, people in the United Kingdom ate contaminated beef without knowing it, the number of vCJD cases is surprising small. Spread of the disease has been controlled by massive slaughter of cattle and changes in how beef is processed in the United Kingdom. Widespread surveillance for the disease in cattle has resulted in a progressively lower number of new cases of vCJD in the United Kingdom. Only one case occurred in 2012. Four cases of vCJD have been diagnosed in the United States, and two have been diagnosed in Canada, but none of them originated in North America.

About 1 in 2,000 people in the United Kingdom have the abnormal prion protein that occurs in vCJD, but they have no symptoms. There is some concern that if these people donate blood or have a surgical procedure, other people may become infected.

Mad cow disease has been reported in a few North American cattle (4 in the United States and 19 in Canada).

Did You Know...

  • The human form of mad cow disease (variant Creutzfeldt-Jakob disease), which is acquired from eating contaminated meat, has occurred in only 229 people total.

CJD acquired during a medical procedure

CJD can also be acquired during a medical procedure (called iatrogenic CJD). For example, it can be acquired when one of the following is done:

  • A cornea or possibly other tissue from a donor with CJD is transplanted.

  • Brain surgery is done with instruments previously used to operate on a person who had CJD.

  • A substance derived from a person with CJD is used for treatment.

  • Blood from a person with CJD is used in a blood transfusion.

Routine cleansing and sterilization procedures do not destroy prions. However, bleach is effective.

Iatrogenic CJD has been acquired when hormones derived from human pituitary glands were used for treatment. For example, the disease developed in some children who were treated with growth hormone derived from pituitary glands of cadavers that contained prions. These hormones are now genetically engineered rather than prepared from cadavers, so there is no longer a risk of CJD.

Four cases of CJD have been transmitted through blood transfusion. In all cases, the disease was acquired from donors affected by the variant form. The last case was reported in 2004.

Symptoms of CJD

The most common early symptoms of CJD—memory loss and confusion—may resemble those of other dementias, such as Alzheimer disease. These symptoms are the first to occur in most people with CJD but eventually develop in all affected people. For others, the first symptom is loss of muscle coordination. In people with vCJD, the first symptoms tend to be psychiatric symptoms (such as anxiety or depression), rather than memory loss. Later symptoms are similar in both forms.

Whether symptoms develop gradually or abruptly, mental function continues to deteriorate, often causing such symptoms as neglect of personal hygiene, listlessness, and irritability. Some people tire easily and become sleepy. Others cannot fall asleep.

Muscles usually begin to jerk involuntarily and quickly (called myoclonus) during the first 6 months after symptoms begin. Muscles may tremble, and people may become clumsy and uncoordinated. Walking becomes unsteady, resulting in staggering (similar to the walk of a person who is drunk). Movements may be slow. Impairment of muscle control may result in unusual postures, such as twisting of the trunk or limbs forward and sideways. Muscles may jerk when stretched. Some people have hallucinations and seizures.

People may startle easily, and the resulting responses, such as jumping when a loud noise is heard, are exaggerated. Startling may trigger muscle jerking.

The muscles that control breathing and coughing are usually impaired, increasing the risk of pneumonia.

Vision may become blurry or dim.

The symptoms worsen, usually much more rapidly than in Alzheimer disease, resulting in severe dementia.

Most people with CJD die within 6 to 12 months after symptoms appear. About 10 to 20% of people survive for 2 years or more. People with vCJD usually survive for about 14 months. Often, the cause of death is pneumonia.

People may have no symptoms for 10 to 20 years after they acquire vCJD.

Diagnosis of CJD

  • Magnetic resonance imaging

  • Analysis of cerebrospinal fluid (obtained by spinal tap)

  • Electroencephalography

Doctors consider CJD in older people when all of the following are present:

  • Mental function is deteriorating quickly.

  • Muscles jerk involuntarily.

  • Their walk is unsteady and staggering.

  • Other dementias have been ruled out by routine testing.

Doctors may suspect vCJD in younger people who have typical symptoms and who have eaten processed beef in the United Kingdom or in other countries where mad cow disease has occurred or where beef is imported from the United Kingdom. They may suspect familial CJD when younger people have relatives with CJD.

Diagnosis may be difficult. Other disorders cause similar symptoms, so doctors check for such disorders, particularly ones that can be treated.

The most useful test is magnetic resonance imaging (MRI). It can detect characteristic changes in the brain, including some that occur only in people with vCJD.

A spinal tap (lumbar puncture) may be done to obtain a sample of cerebrospinal fluid, which is tested for unusual proteins. These proteins are often (but not always) present in people with CJD, and they may be present in many other disorders. Thus, this test can support the diagnosis but cannot confirm or exclude it. A new test can detect tiny amounts of prion in cerebrospinal fluid. This test may detect CJD better than other tests. A similar urine test can detect vCJD.

Electroencephalography (EEG) is usually done to check for characteristic abnormalities in the electrical activity of the brain, which occur in 70% of people with CJD. However, these changes occur late in the disease and may not be present all the time.

Usually, a sample of brain tissue does not need to be examined under a microscope (biopsy) in people while they are alive. However, examination after death (autopsy) is critical to confirm the diagnosis and type of prion disease.

Treatment of CJD

  • Drugs to relieve symptoms

Currently, CJD cannot be cured, and its progress cannot be slowed. The disease is fatal, usually within months or a few years. However, certain drugs may be given to relieve symptoms. For example, the anticonvulsant valproate and the antianxiety drug clonazepam may reduce muscle jerking. Sedative or antipsychotic drugs can sometimes help calm people who are anxious.

General support and care for the person and family members are important. Day care centers and respite and long-term care may be useful. The CJD Foundation provides support and information (see Creutzfeldt-Jakob Disease Foundation ).

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