Creutzfeldt-Jakob Disease
What is Creutzfeldt-Jakob Disease?
Creutzfeldt-Jakob disease (CJD) is a rare, degenerative,
invariably fatal brain disorder. It affects about one person in every one million people per year
worldwide; in the United States there are about 200 cases per year. CJD usually
appears in later life and runs a rapid course. Typically, onset of symptoms
occurs about age 60, and about 90 percent of patients die within 1 year. In the
early stages of disease, patients may have failing memory, behavioral changes,
lack of coordination and visual disturbances. As the illness progresses, mental
deterioration becomes pronounced and involuntary movements, blindness, weakness of
extremities, and coma may occur.
There are three major categories of CJD:
- In sporadic CJD, the disease appears even though the person has no known
risk factors for the disease. This is by far the most common type of CJD and
accounts for at least 85 percent of cases.
- In hereditary CJD, the person has a
family history of the
disease and/or tests positive for a genetic mutation associated with CJD. About 5 to 10 percent
of cases of CJD in the United States are hereditary.
- In acquired CJD, the disease is transmitted by exposure to brain or nervous
system tissue, usually through certain medical procedures. There is no evidence
that CJD is contagious through casual contact with a CJD patient. Since CJD was
first described in 1920, fewer than 1 percent of cases have been acquired CJD.
CJD belongs to a family of human and animal diseases
known as the transmissible spongiform encephalopathies (TSEs). Spongiform refers
to the characteristic appearance of infected brains, which become filled with
holes until they resemble sponges under a microscope. CJD is the most common of the
known human TSEs. Other human TSEs include kuru, fatal familial insomnia (FFI),
and Gerstmann-Straussler-Scheinker disease (GSS). Kuru was identified in people of an isolated tribe in Papua
New Guinea and has now almost disappeared. FFI and GSS are extremely rare
hereditary diseases, found in just a few families around the world. Other TSEs
are found in specific kinds of animals. These include bovine spongiform encephalopathy (BSE), which is found in cows and is often
referred to as “mad cow” disease; scrapie, which affects sheep and goats; mink
encephalopathy; and feline encephalopathy. Similar diseases have occurred in
elk, deer, and exotic zoo animals.
What are the Symptoms of the Disease?
CJD is characterized by rapidly progressive dementia.
Initially, patients experience problems with muscular coordination; personality
changes, including impaired memory, judgment, and thinking; and impaired vision.
People with the disease also may experience insomnia, depression, or unusual
sensations. CJD does not cause a fever or other flu-like symptoms. As the
illness progresses, the patients' mental impairment becomes severe. They often
develop involuntary muscle jerks called myoclonus, and they may
go blind. They eventually lose the ability to move and speak and enter a coma.
Pneumonia and other infections often
occur in these patients and can lead to death.
There are several known variants of CJD. These variants differ somewhat in
the symptoms and course of the disease. For example, a variant form of the
disease-called new variant or variant (nv-CJD, v-CJD), described in Great
Britain and France-begins primarily with psychiatric symptoms, affects younger
patients than other types of CJD, and has a longer than usual duration from
onset of symptoms to death. Another variant, called the panencephalopathic form,
occurs primarily in Japan and has a relatively long course, with symptoms often
progressing for several years. Scientists are trying to learn what causes these
variations in the symptoms and course of the disease.
Some symptoms of CJD can be similar to symptoms of other progressive
neurological
disorders, such as Alzheimer's or
Huntington's disease. However, CJD causes
unique changes in brain tissue which can be seen at
autopsy. It also
tends to cause more rapid deterioration of a person's abilities than Alzheimer's
disease or most other types of dementia.
Next: How is Creutzfeldt-Jakob disease diagnosed? »
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