CJD is thought to be caused by a protein called a prion. A prion causes normal proteins to fold abnormally. This affects the other proteins' ability to function.
There are several types of CJD. The disorder is very rare, occurring in about 1 out of 1 million people. It usually first appears between ages 20 and 70. Symptoms usually start in the late 50s.
CJD can be grouped into two types: classic or new variant disease.
The classic types of CJD are:
Sporadic CJD makes up most cases. It occurs for no known reason. The average age at which it starts is 65.
Familial CJD occurs when a person inherits the abnormal prion from a parent (inherited CJD is rare)
Classic CJD is not related to mad cow disease (bovine spongiform encephalitis).
However, variant CJD (vCJD) is a form of the disease that is related to mad cow disease. The infection that causes the disease in cows is believed to be the same one that causes vCJD in humans.
Variant CJD accounts for less than 1% of cases, and it tends to affect younger people. However, fewer than 200 people worldwide have had this disease.
Variant CJD can be caused by exposure to contaminated products. Other vCJD cases have occurred when people were given corneal transplants, other tissues, or blood transfusions from infected donors. It may also have been caused by contaminated electrodes used in brain surgery (before instruments started to be properly disinfected).
CJD may be related to several other diseases caused by prions, including:
Chronic wasting disease (found in deer)
Kuru (seen in New Guinea women who ate the brains of dead relatives as part of a funeral ritual)
Scrapie (found in sheep)
Other rare human diseases, such as Gerstmann-Straussler-Scheinker disease and fatal familial insomnia
CJD is rarely confused with other types of dementia (such as Alzheimer's disease) because in CJD, the symptoms get worse much more quickly. Both forms of CJD are different than dementia because the symptoms progress quickly to disability and death.
Signs and tests
Early in the disease, a nervous system and mental examination will show memory problems and changes in other mental functions. Later in the disease, a motor system examination may show:
Abnormal reflexes or increased normal reflex responses
There is loss of coordination 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 notice.
Tests used to diagnose this condition may include:
Blood tests to rule out other forms of dementia and to look for markers that sometimes occur with the disease
The disease can only be confirmed with a brain biopsy or autopsy.
There is no known cure for this condition. Interleukins and other medications may help slow the disease. The person may need care early in the disease. Medications may be needed to control aggressive behaviors.
Providing a safe environment, controlling aggressive or agitated behavior, and meeting the person's needs may require monitoring and assistance in the home or in a care facility. Family counseling may help the family cope with the changes needed for home care.
Visiting nurses or aides, volunteer services, homemakers, adult protective services, and other community resources may help care for the person with CJD.
People with this condition may need help controlling unacceptable or dangerous behaviors. This involves rewarding positive behaviors and ignoring negative behaviors (when it is safe). They may also need help getting oriented to their surroundings.
Getting legal help with advance directives, powers of attorney, and other legal actions early in the disorder can make it easier to make ethical decisions about the CJD patient's care.
The outcome of CJD is usually very poor. Within 6 months or less after symptoms begin, the person will be unable to care for himself or herself.
The disorder is fatal in a short time, usually within 8 months. However, a few people survive for as long as 1 or 2 years. The cause of death is usually infection, heart failure, or respiratory failure.
Loss of ability to interact with others
Loss of ability to function or care for oneself
Calling your health care provider
CJD is not a medical emergency. However, getting diagnosed and treated early may make the symptoms easier to control, give patients time to make advance directives, and give families extra time to come to terms with the condition.
Medical equipment should be treated to remove the proteins that may cause the disease. People who have a history of CJD should not donate a cornea or tissue.
Most countries now have strict guidelines for managing infected cows to avoid transmitting CJD to humans.
DeKosky ST, Kaufer DI, Hamilton RL, Wolk DA, Lopez OL. The dementias. In: Bradley WG, Daroff RB, Fenichel GM, Jankovic J, eds. Neurology in Clinical Practice. 5th ed. Philadelphia, Pa: Butterworth-Heinemann Elsevier; 2008:chap 70.
A.D.A.M. Health Solutions, Ebix., Inc., Editorial Team: David Zieve, MD, MHA, and David R. Eltz. Previously reviewed by David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by Luc Jasmin, MD, PhD, Departments of Anatomy and Neurological Surgery, University of California, San Francisco, CA. Review provided by VeriMed Healthcare Network (9/26/2011).