Creutzfeldt-Jakob disease is a rare neurodegenerative disease that rapidly, progressively, and severely affects the brain.

Creutzfeldt-Jakob Disease (CJD) gradually destroys brain cells, and it causes tiny holes in the brain. People with CJD will have ataxia, or difficulty controlling body movements, abnormal gait, speech, and dementia.

It is always fatal, and there is no cure.

CJD affects one person in every million globally each year, including the United States (U.S.).

Causes can be sporadic, inherited, or acquired. It mostly affects people over the age of 60 years, and it is rare in people under 30 years old.

A person with CJD is unlikely to survive longer than one year after symptoms appear.

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CJD is a rare but fatal disease.

CJD is a transmissible spongiform encephalopathy (TSE) that destroys the brain over time. It is caused by an infectious agent, called a prion. A prion is not a virus or bactera.

Other types of TSE include Gerstmann-Sträussler-Scheinker (GSS) syndrome, fatal familial insomnia, and kuru in humans. Other examples are scrapie in sheep and goats, and bovine spongiform encephalopathy (BSE), or "mad-cow disease," in cattle.

Similar encephalopathies and wasting syndromes are found in other species, and they have been shown to be transmissible in laboratory animals.

The Centers for Disease Control and Prevention (CDC) note that classic CJD is not related to BSE or other variants.

CJD has a long incubation period. Symptoms can take up to 40 years to appear. Symptoms occur when brain cells are being destroyed. The patient's condition will deteriorate rapidly within weeks, with most people dying within a year.

The hallmark symptoms of CJD are a rapid progression to dementia and myoclonus, or spasmodic involuntary movement of muscle groups.

Mood or behavior changes, personality changes, memory loss, and impaired judgment are common. The condition may resemble Alzheimer's dementia or Huntington's disease, but symptoms will evolve within days to weeks, rather than years.

As the disease progresses, problems with coordination and myoclonus worsen, and vision becomes impaired, leading to blindness. Eventually, the patient can no longer move or speak, and they will enter a coma.

Autopsies of brain tissue have revealed that CJD involves some unique changes not seen in other dementias.

There are several variants of CJD that are not necessarily related to classic CJD, and the symptoms and course of the disease may be different.

CJD happens when a prion protein, an abnormal kind of amyloid protein, causes abnormalities in other proteins. The buildup and malformation of prions on the brain cells ultimately lead to brain damage and death.

It may be sporadic, inherited, or acquired.

Sporadic CJD

In 85 percent of cases, CJD is sporadic. There are no apparent risk factors.

Inherited CJD

Between 5 percent and 10 percent of cases are inherited. They happen when a change occurs in the gene that controls the formation of prion proteins. There may be a family history of CJD, or a mutation may occur in the egg or sperm cells, putting offspring at risk of developing the disease.

Prions do not contain genetic information, and they do not need genes to reproduce themselves, but a mutation in the gene for the body's normal prion protein can cause prions to act abnormally.

Several different mutations in the prion gene have been identified. The particular mutation found in each family affects how frequently the disease appears, and which symptoms are most noticeable.

Not everyone with mutations in the prion protein gene develop CJD.

Acquired CJD

There is no evidence that any type of CJD can be passed from one person to another, but some procedures have been linked with CJD transmission.

These include:

  • corneal transplant
  • electrode implants
  • dura mater graft, or meningeal graft, which is a graft of the outer coating of the brain
  • use of human growth hormone

Around 1 percent of cases are transmitted by known or highly suspected exposure to affected brain or nervous system tissue.

Bovine spongiform encephalopathy

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Prion malfunction has been linked to CJD.

In the 1990s, one type of CJD was linked to exposure to BSE, which occurs in cattle.

Transmission was thought to be related to food consumption. This variant tended to affect younger patients, and it also lasted for longer.

BSE affects a number of species, including cattle, humans, and cats.

Some scientists believe that an unusual "slow virus" or another organism causes CJD, but they have not yet isolated a specific virus or organism in people with the disease.

The agent that causes CJD has several characteristics that are not usual in viruses and bacteria.

These include the long incubation period, the fact that it is difficult to kill, and that it does not appear to contain any genetic information in the form of nucleic acids, DNA or RNA.

Scientists believe that CJD and other TSEs are caused not by a living organism but by prions. Prions are not alive, but they are proteins with abnormal structures that expand in the brain.

This expansion damages brain tissue and causes the characteristic symptoms of CJD.

There is no test to confirm the diagnosis of CJD. Only a brain biopsy can do this, and this is too risky for the patient while they are alive.

Tests can help to find the most likely cause.

A physical examination will look for muscle spasms and check the patient's reflexes. These may be more reactive than normal. Muscles may be excessively toned or withered, depending on where the disease affects the brain.

A vision or eye test may detect partial blindness that the patient had not previously noticed.

An electroencephalogram (EEG) can reveal abnormal electrical impulses.

A CT scan or MRI can rule out stroke as a cause of symptoms.

A lumbar puncture, or spinal tap, can test spinal fluid to rule out other causes of dementia. It can show if there is an infection or increased pressure in the central nervous system (CNS).

If the protein 14-3-3 is found in the fluid, and the person is showing typical symptoms, there is a high chance that the person has CJD.

Brain biopsies after death show that the brain tissue is spongy, with tiny holes visible where clumps of nerve cells have been destroyed.

There is no cure for CJD, and no medications can help to control it or slow disease progression.

Treatment aims to relieve symptoms and make the patient as comfortable as possible.

Opiate drugs can help to relieve pain. Clonazepam and sodium valproate may help relieve involuntary movements, such as muscle twitching.

In the later stages, the patient must be moved frequently to help prevent bedsores. A catheter can be used to drain urine, and feeding is by intravenous fluids.

Preventive measures include sterilization of all medical equipment to kill any organisms that may cause the disease, and not accepting cornea donations from people with a history of diagnosed or possible CJD.

Most countries now have strict guidelines for management of infected cows and restrictions regarding feed, to avoid the potential for transmission of other forms of TSE to humans.

People who are exposed to individuals with a diagnosis of CJD are advised to follow some guidelines.

These include:

  • covering open wounds, cuts, and abrasions on the skin
  • wearing gloves when handling patient tissue, blood, or fluid
  • wearing a disposable gown or clothing for contact with a patient
  • using a face shield, eye protection or a mask when there is a risk of splashing contaminated fluid
  • sterilizing equipment that has been used on or near the patient

Research is underway into the role of prions in CJD, to find out how the disease affects the brain, and to find an effective treatment.