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Creutzfeldt-Jakob disease (CJD) is an infectious disease that causes the brain to degenerate. The hallmark of this disease is mental deterioration and involuntary muscle spasms. Over time, the disease causes growing problems with memory, personality changes, and dementia. CJD progresses rapidly and can be fatal.
According to the World Health Organization (WHO), CJD occurs all over the world, but it’s not very common. Only one person per million will get the most common form of this illness, known as sporadic CJD. The National Institute of Neurological Disorders and Stroke (NINDS) reports that only 300 cases of CJD are diagnosed per year in the United States.
Symptoms of CJD include:
In variant and classic CJD, dementia causes your mind and body to deteriorate quickly. This is very different from Alzheimer’s-associated dementia, which progresses slowly.
CJD is caused by an infectious agent called a prion. Prions are a type of small protein that are normally found in the tissues of many mammals. In prion disease, these proteins are abnormally folded, and form clumps. When they infect a mammal, its normal proteins start to take on the incorrect structure of the infectious prions. This causes brain injury by destroying nerve cells and disrupting the structure of your brain. CJD is a type of "spongiform" encephalopathy. On brain imaging, people with CJD appear to have holes in their brains where cells have died — causing their brains to resemble a sponge.
There’s strong evidence that the agent responsible for bovine spongiform encephalopathy (BSE) in cows, commonly called "mad cow disease," is also responsible for one form of CJD in humans, called "variant CJD."
BSE affected cattle in the United Kingdom, primarily in the 1990s and early 2000s. Variant CJD (vCJD) first appeared in humans in 1994–1996, about a decade after people first had extended exposure to potentially BSE-contaminated beef. According to the Centers for Disease Control and Prevention, this fits the known incubation periods for CJD. Experimental studies on mice have also provided evidence supporting the link between BSE and vCJD.
The two most common types of human CJD are sporadic CJD and familial CJD.
Sporadic CJD can develop anytime between the ages of 20 and 70. However, it most commonly affects people in their late 50s. Sporadic CJD has no connection to mad cow disease.
Sporadic CJD occurs when normal proteins spontaneously mutate to the abnormal prion type. According to NINDS, at least 85 percent of CJD cases are sporadic. Sporadic CJD is most common in people over the age of 65.
Inherited CJD accounts for 5-15% of CJD. It occurs when you inherit a mutated gene associated with prion disease from a parent. People with inherited CJD often have family members with the disease. The extent of how CJD manifests in separate family members can vary widely and is known as variable expressivity.
Variant CJD or vCJD occurs in both animals and humans. When it appears in cattle, it’s called mad cow disease, or BSE. According to the Mayo Clinic, vCJD affects mostly young people in their late 20s.
You can become infected with vCJD by eating meat that’s contaminated with infectious prions. However, your risk of eating infected meat is very low. You can also become infected after receiving blood or transplanted tissues, such as a corne, from an infected donor. The disease can also be transmitted by surgical instruments that haven’t been properly sterilized. Fortunately, there is rigorous sterilization protocols for instruments that have been in contact with tissue at risk for prion exposure, such as brain or eye tissue.
Despite all the press on mad cow disease, vCJD is very rare. From October 1996 to March 2011, WHO says there were only 224 cases reported worldwide. As of 2013, only three cases of variant CJD have been reported in the United States. Less than 1 percent of people with CJD have the variant type.
The risk of classic CJD increases with age. You can’t get CJD from casual exposure to people who are infected. Instead, you need to be exposed to infected bodily fluids or tissue.
Caregivers of people with CJD should take extra precautions to lower their risk of contracting the disease:
To diagnose CJD, your doctor will begin with a complete medical history, physical examination, and neurological evaluation. The rapid progression of symptoms distinguishes CJD from other causes of dementia. Your doctor can also use a number of tests to establish your diagnosis:
MRI is the most helpful test to diagnose CJD. It can detect small changes to your brain that may suggest CJD. An MRI uses magnetic fields to create images of your brain.
CAT scans not as useful as MRI scans to detect brain changes in CJD. Usually, the CAT scans will be normal. In some patients, rapid degeneration of brain tissue can be detected.
In this test, your doctor will use a thin needle to puncture the lining of your spinal cord to obtain spinal fluid. If your spinal fluid tests positive for elevated levels of a protein called 14-3-3, you may have CJD. However, high levels of protein are also found in many other diseases.
In this test, your doctor will use scalp electrodes to examine your brain waves. If you have CJD, your brain waves may show sharp spikes.
Your doctor can use blood tests to identify and rule out problems such hypothyroidism and syphilis, which can also cause dementia.
It is important to remember that only a biopsy of brain tissue can confirm a diagnosis of CJD.
There is no known cure or effective treatment for CJD. However, medications can be used to treat some of the mental changes and personality abnormalities that occur. Your course of treatment will probably focus on making you comfortable and helping you function safely in your environment.
Sadly, according to NINDS, 90 percent of people with classic CJD die within a year. People with variant CJD tend to survive a little longer, from the onset of symptoms to death.
Symptoms of CJD will get worse until you lapse into a coma. The most frequent causes of death for people with CJD are:
Speak with your doctor about strategies to manage your symptoms.
Written by: Verneda Lights
Medically reviewed on: Feb 26, 2016: University of Illinois-Chicago, College of Medicine
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