Creutzfeldt-Jakob Disease (CJD)

Creutzfeldt-Jakob disease (CJD) is a fatal disease that affects the brain. It is a form of human spongiform encephalopathy (SPUN-ji-form en-sef-a-LOP-a-thee), which means it causes the brain to become sponge-like as it deteriorates.


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Neuromuscular system



Spongiform encepholopathies

What Is Creutzfeldt-Jakob Disease (CJD)?

Creutzfeldt-Jakob disease is a slowly progressing disease of the brain. While most people who contract the disease die within several months, some people decline slowly and may live several years after they are diagnosed. Creutzfeldt-Jakob disease usually affects older people.

Since Creutzfeldt-Jakob disease affects the brain, its primary symptom is dementia (de-MEN-sha). Some signs of dementia are disorientation, neglect of personal hygiene and grooming, and irritability. Other symptoms include fatigue, insomnia, and muscle twitching or sudden contractions. Medical treatment focuses on making people with CJD as comfortable as possible as a cure does not exist yet.

How Widespread Is Creutzfeldt-Jakob Disease?

Creutzfeldt-Jakob disease is rare. About 200 people are reported to have the disease in the United States, and it affects approximately 1 person per million worldwide. Mostly, if affects older people: approximately 6 people in every million worldwide between the ages of 70 to 74, with the mean age of death from CJD now at 67 years. About 90 percent of cases are reported to lead to death within 1 year after symptoms begin, with the remaining 10 percent of people with CJD declining over a 1-to 2-year period. Because CJD usually is a slowly progressing disease, symptoms may not begin for as long as 20 years after infection.

What Causes Creutzfeldt-Jakob Disease?

Creutzfeldt-Jakob disease is caused when a molecule called the prion protein, which is normally found in the brain, becomes abnormal. Scientists are not sure how prions ("proteinaceous infectious particles") work or how they cause disease.

Scientists are studying several types of CJD:

  • In sporadic CJD, the gene * coding for the prion protein mutates (changes) spontaneously and begins to produce the abnormal prion protein. This protein can infect other brain cells.
  • In genetic CJD, a mutated gene for the prion protein is inherited and passed from one generation to the next.
  • In iatrogenic (i-at-ro-JEN-ik) CJD, the disease is transmitted from an infected person to a healthy person during a medical procedure such as transplant surgery or from receiving human growth hormone derived from the pituitary gland of an infected person.

"Mad Cow Disease"

In 1986, a brain disease called bovine (BO-vyne) spongiform encephalopathy (BSE) was discovered in cows. Termed "mad cow disease" because the infected cows stumbled and lost muscular coordination, the disease had been transmitted to the cows from feed made from ground sheep bones and parts. The sheep had a disease called scrapie (SCRAP-ee), which had been passed on to the cattle.

* genes are chemicals in the body that help determine a person's characteristics, such as hair or eye color. They are inherited from a person's parents and are contained in the chromosomes found in the cells of the body.

It was thought that mad cow disease could not be passed on to people, but the British Ministry of Health discovered a variant form of BSE in people younger than the average age for CJD cases. Countries all over Europe and other parts of the world began to ban the import of beef from Britain, and millions of cattle in Britain were killed in order to avoid spreading the disease. Many people turned to vegetarian diets, and many restaurants stopped serving beef.

See also
Alzheimer's Disease


U.S. National Institute of Neurological Disorders and Stroke (NINDS), Bethesda, MD 20892. NINDS posts a fact sheet about CJD at its website. The fact sheet includes referrals to other resources.

Creutzfeldt-Jakob Disease Foundation, P.O. Box 611625, North Miami, FL 33261-1625.

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