Creutzfeldt-Jakob disease (CJD) is a rare neurodegenerative condition. It has severe effects on the brain.
CJD gradually destroys brain cells and causes tiny holes to form in the brain.
People with CJD experience difficulty controlling body movements, changes in gait and speech, and dementia.
There is no cure for the disease. It progresses quickly and every case is fatal. A person usually dies within 1 year after symptoms appear.
There are different types of CJD. It can develop sporadically, without any identifiable pattern. It can be inherited and may be transmitted.
“Classic” CJD develops in people aged over 60 and affects one person in every million each year, globally.
Another type, called variant CJD (vCJD), affects younger people.
A person can acquire vCJD after eating the meat of a cow that has bovine spongiform encephalopathy, commonly called mad cow disease. However, developing vCJD in this way is rare.
What is CJD?
CJD is a transmissible spongiform encephalopathy (TSE) that destroys the brain over time.
CJD is caused by a prion, a misfolded protein that can transmit its malformation to healthy variants of the same protein.
Other types of TSE in humans include Gerstmann-Sträussler-Scheinker syndrome, fatal familial insomnia, and kuru. Examples in other animals include scrapie, in sheep and goats, and bovine spongiform encephalopathy, in cattle.
Laboratory tests indicate that transmission can occur between animals, but this does not necessarily mean that CJD is transmissible between humans.
However, transmission may be possible, for example, through transfusions or transplants of infected blood or tissues.
Transmission does not occur through casual contact.
CJD has a long incubation period. Symptoms may take decades to appear.
Symptoms emerge as the disease destroys brain cells. The person’s condition will deteriorate rapidly. The symptomatic period lasts 4–5 months on average, and the disease is usually fatal within 1 year.
The hallmark symptoms of CJD are a rapid progression of dementia and myoclonus — spasmodic, involuntary movement of muscle groups.
Other common symptoms of CJD include:
- changes in mood, personality, or behavior
- memory loss
- impaired judgment
The condition may resemble Alzheimer’s dementia or Huntington’s disease, but the symptoms take days or weeks to develop, rather than years.
As the disease progresses, problems with coordination and muscle control worsen. Over time, the person will lose their vision and their ability to move and speak. Eventually, they will enter a coma.
Autopsies of brain tissue have revealed that CJD leads to certain changes that do not occur with other causes of dementia.
There are several types of CJD. The symptoms and progression of each may vary.
Scientists believe that prions are responsible for CJD and other TSEs.
A prion is a type of protein with an abnormal structure, and it passes this abnormality on to other proteins. This damages brain tissue and cause the characteristic symptoms of CJD.
Prions have a long incubation period and are difficult to target. They also contain no genetic information in the form of nucleic acids, such as DNA or RNA.
CJD may be inherited or acquired. In some cases, it develops sporadically, without an identifiable pattern.
In 85% of cases, CJD is sporadic. This means that there is no clear reason why it develops.
A person may have a family history of CJD. Between 10% and 15% of CJD cases are inherited.
The disease can develop if a change occurs in the gene that controls the formation of prion proteins.
Prions do not contain genetic information, and they do not need genes to reproduce. However, a genetic mutation can cause prions to act abnormally.
Scientists have identified several mutations in the prion gene. The specific mutation can affect how frequently the disease appears in a family and which symptoms are most noticeable.
However, not everyone who has prion gene mutations will develop CJD.
There is no evidence that CJD can pass from one person to another through casual contact.
However, transmission may occur during the use of human growth hormone or during procedures that involve affected brain or nervous system tissue. These procedures may include:
- corneal transplantation
- electrode implantation
- meningeal graft, a graft of the outer coating of the brain
Fewer than 1% of CJD cases are acquired.
It is possible to acquire vCJD, not classic CJD, by eating meat from a cow that had bovine spongiform encephalopathy. A person cannot acquire classic CJD through food.
No test can confirm a diagnosis of CJD. Only a brain biopsy can do this, and the procedure is too risky when a person is alive.
However, some tests and imaging techniques can help a doctor make a diagnosis.
During aphysical examination, the doctor will look for muscle spasms and check the person’s reflexes. These may be more reactive than usual.
Also, the muscles may be excessively toned or withered, depending on where the disease affects the brain.
Avision or eye test may detect vision loss, and anEEG can reveal unusual electrical impulses that can characterize the disease.
CAT scan or MRI can rule out stroke as a cause of symptoms. MRI scans may also show changes characteristic of CJD.
A doctor can test spinal fluid using lumbar puncture, also known as a spinal tap, to rule out other causes of dementia. This test can show whether there is an infection or increased pressure in the central nervous system.
If the 14-3-3 protein is present in the spinal fluid and the person has typical symptoms, this may indicate CJD.
Brain biopsies after death show that the brain tissue is spongy, with tiny holes where clumps of nerve cells have been destroyed.
There is no cure for CJD, and no medications can control it or slow its progression. Scientists are looking into several treatment options for future use.
Currently, doctors aim to relieve symptoms and make the person as comfortable as possible.
Opiate drugs can help relieve the pain. Also, clonazepam and sodium valproate may help relieve involuntary movements, such as muscle twitching.
In the later stages, a carer will move the person frequently to help prevent bedsores. A catheter will drain the person’s urine, and they will receive nutrients intravenously.
In a hospital setting, preventive measures include:
- sterilizing all medical equipment
- not accepting cornea donations from people with a risk of CJD
Anyone who is caring for a person with CJD should follow some guidelines, including:
- covering open wounds, cuts, and abrasions on the skin
- wearing gloves when handling tissue, blood, or fluid
- wearing a disposable gown or clothing
- using a face shield, eye protection, or a mask when there is a risk of splashing contaminated fluid
- sterilizing equipment used on or near the person
- using disposable bedclothes or soaking linens in a chlorine solution for at least 1 hour
Scientists continue to investigate how CJD affects the brain, in an effort to develop effective treatments.
To avoid the potential transmission of TSEs to humans, most countries now have restrictions in place, including strict guidelines for managing infected cows.
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