Creutzfeldt-Jakob disease (CJD) is a form of brain damage that causes a rapid decrease of mental function and movement.

CJD is believed to result from a protein called a prion. A prion folds abnormally. This seems to encourage other proteins to have bad shapes, which affects their ability to function.

There are several types of CJD. The disorder is rare, occurring in about 1 out of 1 million people. It usually first appears between ages 20 and 70, with average age at onset of symptoms in the late 50s.

CJD can be grouped into classic or new variant disease.

The classic types of CJD are:

• Sporadic CJD makes up the most cases. It often occurs for no known reasons.
• Familial CJD results when a person inherited the abnormal protein (prion). Inherited CJD is rare.

Classic CJD is not related to mad cow disease (bovine spongiform encephalitis).

However, new variant CJD (nvCJD) is an infectious form that is related to mad cow disease. The infection responsible for the disease in cows is believed to be the same one responsible for vCJD in humans.

New variant CJD accounts for less than 1% of cases, and tends to affect younger people. It can result when someone is exposed to contaminated products.

Some cases of nvCJD have occurred in adolescents who have received growth hormone made from the pituitary glands of cadavers (dead bodies). Prions cannot be destroyed by ordinary disinfection techniques used to prevent transmission of viruses and bacteria. As a result, the hormone remains contaminated. Cadaver-derived growth hormone has been replaced by synthetically manufactured growth hormone, so this source of contagion is no longer a problem.

Other nvCJD cases have occurred when people were given corneal transplants from infected donors, and from contaminated electrodes that were used in brain surgery (before it was known how to properly disinfect instruments).

There have not been any cases of nvCJD reported in the U.S.

CJD may be related to several other diseases also thought to be caused by prions, including kuru (seen in New Guinea women who ate the brains of deceased relatives as part of a funerary ritual), scrapie (found in sheep), and other rare human diseases, such as Gerstmann-Straussler-Scheinker disease and fatal familial insomnia.

• Blurred vision (sometimes)
• Changes in gait (walking)
• Hallucinations
• Lack of coordination (for example, stumbling and falling)
• Muscle twitching
• Muscle stiffness
• Myoclonic jerks or seizures
• Nervous, jumpy feelings
• Personality changes
• Profound confusion, disorientation
• Rapidly developingdelirium or dementia
• Sleepiness
• Speech impairment

Additional symptoms that may be associated with this disease:

• Memory loss
• Anxiety, stress, and tension

Once symptoms appear, the disorder progresses rapidly and may be confused with other types of dementia -- like Alzheimer's disease. Both forms of CJD, however, are distinguished by extremely rapid progression from onset of symptoms to disability and death.

A neurological and motor system examination shows muscle twitching and spasm. There is a strong startle response. Muscle tone may be increased, or there may be weakness and muscle wasting (loss of muscle tissue). There may be abnormal reflexes or an increase in the response of normal reflexes.

There is loss of coordination related to visual-spatial perception changes and changes in the cerebellum, the area of the brain that controls coordination (cerebellar ataxia). An eye examination shows areas of blindness that the person may not realize are present.

Tests used to diagnose this condition may include:

• EEG
• Spinal tap

Ultimately, the disease can only be confirmed by brain biopsy or autopsy.

There is no known cure. Custodial care may be required early in the course of the disease. Medications may be needed to control aggressive behaviors. These include sedatives, antipsychotics, and others.

Provding a safe environment, controlling aggressive or agitated behavior, and meeting physiologic needs may require monitoring and assistance in the home or in an institutionalized setting. Family counseling may help in coping with the changes required for home care.

Visiting nurses or aides, volunteer services, homemakers, adult protective services, and other community resources may be helpful in caring for the person with CJD.

Behavior modification may be helpful, in some cases, for controlling unacceptable or dangerous behaviors. This consists of rewarding appropriate or positive behaviors and ignoring inappropriate behaviors (within the bounds of safety). Reality orientation, with repeated reinforcement of environmental and other cues, may help reduce disorientation.

Legal advice may be appropriate early in the course of the disorder to form advance directives, power of attorney, and other legal actions that may make it easier to make ethical decisions regarding the care of an individual with CJD.

The outcome is usually very poor. Complete dementia commonly occurs within 6 months or less of the onset of symptoms, with the person becoming totally incapable of self-care.

The disorder is fatal in a short time, usually within 7 months, but a few people survive as long as 1 or 2 years after diagnosis of the disorder. The cause of death is usually infection, heart failure, or respiratory failure.

• Infection
• Heart failure
• Respiratory failure
• Loss of ability to function or care for oneself
• Loss of ability to interact with others
• Death

CJD is not a medical emergency, but early diagnosis and treatment may make the symptoms easier to control, allow patients time to make advance directives, and give families additional time to come to terms with the condition.

Medical equipment is sterilized to kill organisms that may cause the disease. Persons who have a medical history of diagnosed or possible CJD are not used as cornea donors.

Most countries now have strict guidelines for management of infected cows and strict restrictions regarding what they are fed, to avoid the potential for transmission of CJD to humans.

Llewelyn CA, Hewitt PE, et al. Possible transmission of variant Creutzfeldt-Jakob disease by blood transfusion. Lancet 2004;363:417-421.

Peden AH, Head MW, et al. Preclinical vCJD after blood transfusion in a PRNP codon 129 heterozygous patient. Lancet 2004;264:527-529.

Brown P, Will RG, Bradley R, Asher DM, Detwiler L. Bovine Spongiform Encephalopathy and Variant Creutzfeldt-Jakob Disease: Background, Evolution, and Current Concerns. EID. January-February 2001; 7(1):6-16.

Noble J. Textbook of Primary Care Medicine. 3rd ed. St. Louis, Mo: Mosby; 2001:1551-1569.