Home > Diagnosis, Types of dementia > What Is Creutzfeldt-Jacob Disease?

What Is Creutzfeldt-Jacob Disease?

Creutzfeldt-Jacob Disease is a disorder which produces one of the more rare forms of dementia; however it has gotten a lot of attention in the media lately because of its association with something known as Mad Cow Disease.  The fact of the matter is that this variant form of CJD occurs in approximately one percent of a rare disease which affects only one person in a million worldwide.  A more in-depth explanation of the disorder is being provided here, due to the increased public interest it has received in the last several years.

CJD is one of a group of disorders known as prion diseases.  Prion is a protein which is normally found throughout the body.  But, for some reason, it occasionally mutates into a form which can cause disastrous results when introduced to the brain.  Through a process which is not entirely understood yet, these abnormal prions begin to destroy brain cells.  This causes a rapid deterioration of cognitive and motor skills (voluntary and involuntary) and psychiatric problems.

CJD belongs to a family of human and animal diseases known as transmissible spongiform encephalopathy (TSE).  The term spongiform refers to the unique appearance of infected brains; they become so filled with holes that they resemble a sponge when viewed under a microscope.  CJD is the most well-known of the human TSEs, but others include kuru, fatal familial insomnia (FFI), and Gerstmann-Straussler-Scheinker disease (GSS).  Kuru is a disease peculiar to an isolated tribe living in New Guinea, and has at present been nearly eradicated.  FFI and GSS are also extremely rare diseases found exclusively in a very few families around the world.  Other TSEs are found in certain kinds of animals, and include bovine spongiform encephalopathy (BSE), scrapie, mink encephalopathy, and feline encephalopathy.  BSE is found in cattle that are given feed which contains brain matter from infected animals, and is the disorder commonly referred to as “mad cow disease.”  Scrapie is a disorder found in sheep and goats.

There are three main categories of CJD:

  1.  Sporadic – Accounting for 85% of cases, or more, symptoms develop in spite of the total absence of any risk factors.  It occurs spontaneously, often for no identifiable reason, and typically appears between the ages of 60 and 65.
  2. Hereditary – Occurring in about five to ten percent of cases, the disease is associated with a genetic mutation and/or a family history.
  3. Acquired – Transmitted through exposure to infected brain or nervous tissue, usually through medical procedures.  (There is absolutely NO evidence that CJD is contagious through casual contact with infected persons.)  Since 1920, only one percent of all cases of CJD have been acquired through this kind of contact.

Symptoms of CJD include a rapidly progressing dementia, which becomes severe in the latter stages of the disease.  In some ways, it can initially appear similar to Alzheimer’s disease or Huntington’s disease, but its characteristic changes in the brain will be noticeable at autopsy.  In the early stages, persons with the CJD show difficulty with muscular coordination and personality changes (agitation, apathy, mood swings), as well as visual impairments.  Memory, judgment, and thinking become disordered.  Insomnia, depression, and unusual sensory experiences are not uncommon.  Eventually, individuals with the disease may develop characteristic involuntary jerking motions of the muscles (myoclonus), and may become blind, before losing the ability to speak and slipping into a coma.  Death is usually due to secondary infections such as pneumonia.

Several alternate forms of CJD exist, with some diversity as to symptomology and progression.  One variant, v-CJD, which has been noted in Great Britain and France, develops earlier, and progresses more slowly, than the classic version of the disease.  It typically begins with psychiatric symptoms.  Another version, the panencephalopathic form, has a much slower progression (sometimes several years) and is found primarily in Japan.

Diagnosis of CJD is similar, in many ways, to that of other forms of dementia.  The process will usually start with ruling out other causes for the symptoms and behaviors displayed by the patient.  An overall physical exam by one or more medical specialties will generally include a neurological work-up.  Laboratory tests may include a spinal tap, to rule out other causes such as encephalitis or meningitis, and an EEG, which will show a particular type of deviation in CJD.  Brain imaging will also most likely be performed.  There is also some promising research being done to create a test of the person’s cerebrospinal fluid for a protein marker specific for the disease.  One feature that will typically distinguish CJD from other forms of dementia is the rapid progression of the disease.

As with other forms of dementia, the only way to definitely confirm or deny the presence of CJD is at autopsy, with dissection of brain tissue.  It is possible, while the patient is still living, to perform a brain biopsy, in which a small specimen of brain tissue is removed for study.  Such a procedure is extremely dangerous, however, and there is a very slim chance of actually finding the particular part of the brain that is diseased.  There is also a risk (small, but present nevertheless) that the surgeon who handles the brain will himself be exposed to CJD.  Since this procedure will not contribute to any real positive outcome for the particular patient involved, it is usually highly discouraged.

The exact cause of CJD has yet to be identified.  Some research points to a slow-acting virus or other organism, however none has as yet been isolated.  Other researchers point out that the disease has a number of characteristics that cannot be explained by an infectious process.  It is important to note that CJD cannot be transmitted through the air or by casual contact.  It is typically spread through exposure to brain tissue or cerebrospinal fluid, and care should be taken when handling these materials.  It has occasionally happened that the disease has been spread through transplantation of corneas, grafting of brain tissue, implantation of inadequately sterilized electrodes in the brain, and injections of contaminated pituitary growth hormone.  Since 1985, all human growth hormone used in the U.S. has been synthetically produced, to prevent contamination.

The discovery of several persons infected with v-CJD, starting in the 1990s, led to theories that they had been exposed to beef contaminated with bovine spongiform encephalopathy.  Although research has shown a strong similarity between the two diseases, there is no direct evidence to show that one is responsible for the other.

Some animal studies have shown that it is possible to transmit CJD through transfusions of blood and related products, but this process has not been demonstrated in humans.  Of the millions of people who receive blood transfusions every year, there is not yet one reported case of someone developing the classic form of CJD as a result.  However, there is a policy in place that prevents a person from donating blood who has lived for at least 3 months in a country where v-CJD is common, as a safeguard against such contamination.

There is no known medication that will slow down or stop the progression of CJD.  Pain-killers, muscle relaxants, and anti-seizure drugs do sometimes provide some relief.  Research is on-going, but this is limited by the typically short duration between onset of the disease and death.  (It is estimated that 90% of those diagnosed with sporadic CJD will die within one year, while those affected with the familial version or with v-CJD will survive somewhat longer.)   Treatment tends to focus on alleviation of symptoms, and support for the individual with the disease and his/her friends and family.

  1. June 17, 2014 at 7:37 PM

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