Stanford Center for Memory Disorders

Creutzfeldt-Jakob Disease (Prion Disease)

CJD is a rare, degenerative, fatal brain disorder that affects about one in every million people per year worldwide. Symptoms usually begin after age 60 and most patients die within 1 year. Many researchers believe CJD results from an abnormal form of a protein called a prion. Most cases of CJD occur sporadically - that is, in people who have no known risk factors for the disease. However, about 5 to 10 percent of cases of CJD in the United States are hereditary, caused by a mutation in the gene for the prion protein. In rare cases, CJD can also be acquired through exposure to diseased brain or nervous system tissue, usually through certain medical procedures. There is no evidence that CJD is contagious through the air or through casual contact with a CJD patient.

Patients with CJD may initially experience problems with muscular coordination; personality changes, including impaired memory, judgment, and thinking; and impaired vision. Other symptoms may include insomnia and depression. As the illness progresses, mental impairment becomes severe. Patients often develop myoclonus and they may go blind. They eventually lose the ability to move and speak, and go into a coma. Pneumonia and other infections often occur in these patients and can lead to death.

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 when viewed under a microscope. CJD is the most common of the known human TSEs. Others include fatal familial insomnia and Gerstmann-Straussler-Scheinker disease (see below). In recent years, a new type of CJD, called variant CJD (vCJD), has been found in Great Britain and several other European countries. The initial symptoms of vCJD are different from those of classic CJD and the disorder typically occurs in younger patients. Research suggests that vCJD may have resulted from human consumption of beef from cattle with a TSE disease called bovine spongiform encephalopathy (BSE), also known as "mad cow disease."

Other Prion Diseases

Other rare hereditary prion diseases dementias include Gerstmann-Straussler-Scheinker (GSS) disease and fatal familial insomnia. Symptoms of GSS typically include ataxia and progressive dementia that begins when people are between 50 and 60 years old. The disease may last for several years before patients eventually die. Fatal familial insomnia causes degeneration of a brain region called the thalamus, which is partially responsible for controlling sleep. It causes a progressive insomnia that eventually leads to a complete inability to sleep. Other symptoms may include poor reflexes, dementia, hallucinations, and eventually coma. It can be fatal within 7 to 13 months after symptoms begin but may last longer.

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