Diagnosed independently by Drs. Creutzfeldt and Jakob in the early 1920s, the disease that bears their names is a rare, degenerative brain disorder that affects approximately one person per million per year worldwide. This translates into 250-300 new U.S. cases annually. However, because Creutzfeldt–Jakob Disease (CJD) is very difficult to diagnose, this number may actually be higher. CJD affects men and women of all cultural backgrounds, with symptoms appearing most often in those aged 50 to 75.
Creutzfeldt–Jakob Disease is known as a prion disease, which means that healthy brain tissue deteriorates into an abnormal protein that the body cannot break down. CJD is a type of transmissible spongiform encephalopathy (TSE), a classification that includes both human and animal diseases. "Spongiform" refers to the characteristic appearance of an infected brain, which becomes filled with holes until it looks like a sponge under a microscope.
Prior to the "mad cow disease" epidemic of the 1990s, few people had heard of Creutzfeldt–Jakob Disease. However, once a growing number of young people in the United Kingdom started developing symptoms that appeared congruent with CJD, the world became alarmed. This new form of the illness, named variant Creutzfeldt–Jakob Disease or vCJD, results only from exposure to beef that is contaminated with bovine spongiform encephalopathy (BSE), the scientific term for mad cow disease.
There are four types of Creutzfeldt–Jakob Disease: sporadic (or classical), inherited (or familial), iatrogenic (or acquired) and variant.
|Four Types of Creutzfeldt–Jakob Disease|
Sporadic or classical (sCJD)
The most common form of Creutzfeldt–Jakob Disease, sporadic CJD occurs for an as-yet unknown reason, and accounts for about 85% of the cases. The illness is shorter than in other forms, and predominantly affects adults aged 50+.
Inherited or familial
Caused by a genetic mutation, inherited CJD accounts for fewer than 15% of all Creutzfeldt–Jakob cases. The age of onset can be younger than for sporadic CJD, and the course of illness is generally longer.
Iatrogenic means the disease is acquired through a medical procedure such as contamination from brain surgery, or a corneal transplant, or grafts of dura mater, the membrane that covers the brain and spinal cord. These account for a tiny percentage of cases.
Acquired from eating beef tainted with bovine spongiform encephalopathy (BSE), variant Creutzfeldt–Jakob Disease is more commonly known as mad cow disease. So far, most cases have occurred in the UK. The age of onset is typically younger and the duration of the disease longer than in sporadic CJD.
|Four Types of Creutzfeldt–Jakob Disease|
Sporadic or classical (sCJD) - The most common form of Creutzfeldt–Jakob Disease, sporadic CJD occurs for an as-yet unknown reason, and accounts for about 85% of the cases. The illness is shorter than in other forms, and predominantly affects adults aged 50+.
Inherited or familial - Caused by a genetic mutation, inherited CJD accounts for fewer than 15% of all Creutzfeldt–Jakob cases. The age of onset can be younger than for sporadic CJD, and the course of illness is generally longer.
Iatrogenic - Iatrogenic means the disease is acquired through a medical procedure such as contamination from brain surgery, or a corneal transplant, or grafts of dura mater, the membrane that covers the brain and spinal cord. These account for a tiny percentage of cases.
Variant (vCJD) - Acquired from eating beef tainted with bovine spongiform encephalopathy (BSE), variant Creutzfeldt–Jakob Disease is more commonly known as mad cow disease. So far, most cases have occurred in the UK. The age of onset is typically younger and the duration of the disease longer than in sporadic CJD.
For a long time, researchers believed a "slow virus" was responsible for causing transmissible spongiform encephalopathies (TSEs), of which Creutzfeldt–Jakob Disease is one type. In animals, a TSE known as scrapie has affected sheep and goats since the 1700s. In fact, many experts believe British cattle developed mad cow disease after being fed the remains of scrapie-infected sheep. But the cause of TSEs themselves remained a mystery until the 1980s, when a researcher at the University of California San Francisco suggested the cause was actually an infectious protein, which he named a prion.
Prions (short for proteinaceous infectious particles) are chains of amino acids (the building blocks of proteins) that occur naturally in both human and animal brains, and are normally harmless. However, when the prion folds incorrectly into a shape that can't be used by the body, the accumulating protein deposit begins to cause serious problems. Instead of performing a useful function, the errant prions start to create a slow systemic decline. As diseased cells die, the released prions infect more cells, until the brain eventually resembles Swiss cheese.
This knowledge of brain changes associated with CJD doesn’t explain how the disease begins. We do know that a small number of cases are caused by ingesting infected meat, or medical errors or heredity; but the vast majority of cases have not been traced to a particular cause. Researchers do believe that CJD is not contagious in the usual sense: one cannot catch it as one would a cold or the flu.
Part of the reason CJD is hard to diagnose is that in the early stages, symptoms often appear similar to those of other dementias, such as Alzheimer's Disease, Huntington's Disease, Pick's Disease, or Parkinson's. CJD also has a very long incubation period—up to 30 years. In familial CJD, symptoms typically do not appear until the second half of life, when the gene may have already been passed unwittingly to offspring. Symptoms also vary depending on the type of CJD a patient has.
Early symptoms for both sporadic and iatrogenic CJD can include:
- mood swings
- memory lapses
- social withdrawal
- clumsiness or lack of coordination
In inherited Creutzfeldt–Jakob Disease, initial symptoms may include some or all of the above, as well as:
- visual disturbances
- bizarre behavior
While the initial symptoms of variant CJD are more psychiatric in nature, often leading to incorrect medical referrals, after several weeks or months more obvious neurological symptoms usually appear.
As the disease rapidly progresses, patients with all forms of CJD generally experience:
- visual deterioration and eventual blindness
- involuntary muscle contractions
- muscle paralysis
- slurred speech
- difficulty swallowing
There is not yet a cure for Creutzfeldt–Jakob Disease; only treatment for relieving symptoms. Current clinical trials are testing promising antiviral drugs such as amantadine, which has proved helpful in treating Parkinson's disease. Some patients taking these antivirals have shown brief periods of improvement, with no harmful side effects. However, no treatment has been discovered that stopsCJD completely. It is invariably fatal, often within a year of the onset of symptoms.
The mad cow disease crisis in the UK has generated a great deal of research focus on Creutzfeldt–Jakob Disease and prions. Scientists use rodent models of CJD and brain tissue from autopsies to help advance their inquiries. Among the many areas being studied are:
- the unique nature of prions, which are virtually indestructible;
- factors that influence susceptibility to the disease and that affect when in life symptoms will manifest;
- new, reliable diagnostic tests that will be able to detect CJD before symptoms appear;
- the use of antibodies for the prevention and treatment of prion diseases;
- the possible development of a vaccine.
In addition, two clinical trials studying the effect of the medication quinacrine on CDJ and on human prion disease are currently recruiting patients.
Resources & References
CJD Helpline – A U.S.-based organization that provides information and phone support through a national toll-free number: (800) 659-1991. (CJD Foundation)
CJD Support Network – A charitable organization based in the UK that provides practical, emotional and financial support for caregivers along with latest news updates and important links to related sites. (CJDSupport.net)
Creutzfeldt–Jakob Disease Fact Sheet – Defines CJD, along with symptoms, diagnosis, causes, treatment, and research being done. Includes links to additional useful sites. (National Institute of Neurological Disorders and Stroke)
CJD Information – Provides an overview of the disease and information on advocacy, family support and end-of-life issues. Also links to helpful 24-page PDF pamphlet. (Creutzfeldt–Jakob Disease Foundation, Inc.)
Medline Plus: Creutzfeldt–Jakob Disease – Contains links to wide range of articles relating to many aspects of CJD including breaking news, clinical trials and genetic studies. (National Library of Medicine/National Institutes of Health)
Creutzfeldt–Jakob Disease – Explains crucial diagnostic link between CJD and "mad cow disease". Covers signs and symptoms, causes, risk factors, screening and diagnosis, treatment and prevention. (MayoClinic.com)
About CJD – Information clearinghouse formed after death of founder's mother from CJD. Provides CJD information packet for use in lectures and presentations. (CJD Aware!)
About Human Prion Diseases – Tracking information on the incidence of prion diseases (which includes CJD) in the U.S., types of CJD and forms of transmission. (National Prion Disease Pathology Surveillance Center)
Creutzfeldt–Jakob Disease and Related Disorders – A clear and detailed background on the origins and history of CJD. (University of Minnesota Biomedical Library)/p>
The National Creutzfeldt–Jakob Disease Surveillance Unit (UK) – Extensive list of links to articles and sites covering variant CJD, care and support, clinical aspects and research. (University of Edinburgh)