What is Creutzfeldt-Jakob Disease (CJD)?

What is Creutzfeldt-Jakob Disease (CJD)?

Creutzfeldt-Jakob disease (CJD) is a rare disease that causes fast deterioration of an affected person’s brain. As this condition worsens and damages your brain, it causes dementia-like symptoms.

With CJD, faulty proteins, known as prions, build up in your brain cells, damaging and destroying those cells. The condition is very severe, and its effects develop and worsen quickly. It’s ultimately fatal, and unfortunately, there’s no way to cure, treat or even slow down the progress of this disease.

Who does it affect?

Creutzfeldt-Jakob (pronounced “croy-tz-felt ya-cob”) disease typically affects people between ages 50 and 80, becoming more common as you get older. However, the genetic subtype of CJD usually happens earlier, most often between ages 30 and 50. It affects men and women at equal rates overall.

Variant CJD

One of the subtypes of CJD, known as variant CJD (vCJD), affects people who ate beef that came from cattle infected with bovine spongiform encephalopathy (BSE).

How common is this condition?

CJD is very rare, with 1 to 2 cases happening in every 1 million people worldwide. About 350 people receive a diagnosis of CJD in the U.S. each year.

What happens when you have Creutzfeldt-Jakob disease?

CJD is a degenerative brain disease, meaning it causes damage to your brain that worsens over time. Experts classify it as a “transmissible spongiform encephalopathy” (TSE). The incubation period, which is the time it takes from when you first get the disease to when it starts causing symptoms, can range from months to years.

TSE conditions cause small pockets, or clusters, of damage throughout your brain. This damage causes your brain to look like a sea sponge or to have many holes or hollows like Swiss cheese.

As this brain damage happens, you lose the abilities controlled in the affected area. Overall, people with CJD develop a wide range of symptoms, including memory loss, problems thinking, uncontrolled muscle spasms or movement difficulties, and more. CJD is ultimately fatal because of how much damage it causes.

Symptoms and Causes

What are the symptoms of Creutzfeldt-Jakob disease?

The most common symptoms, listed in order from early to late stages of the disease, include:

  • Forgetfulness and memory problems.
  • Confusion and disorientation.
  • Behavior and personality changes.
  • Problems with your vision or processing and understanding what you see.
  • Hallucinations or delusions.
  • Problems with muscle coordination (ataxia).
  • Balance problems, affecting stability while walking or standing.
  • Uncontrolled muscle movements and spasms (dystonia).
  • Seizures.
  • Paralysis.
  • Wasting (when you lose muscle mass and weight rapidly, sometimes known as muscle atrophy).

What causes Creutzfeldt-Jakob disease?

Faulty proteins in your brain known as prions cause CJD. Proteins are chemical molecules that need to hold a specific shape to work (like how a lock opens for a key with the right shape).

Your cells can’t use proteins when they aren’t the right shape, and your body can’t break them down. With nowhere to go, those proteins slowly build up in your brain cells (neurons), ultimately damaging and destroying the neurons. When your body makes faulty proteins for any reason, those misshapen proteins can cause degenerative brain diseases, like Alzheimer’s disease.

But prion-based diseases have a key difference. Instead of a slow build-up of faulty proteins, prions convert normal proteins into more prions. As the number of prions grows, they turn more proteins into prions. The more prions there are, the faster the conversion happens. That’s why CJD goes from mild behavior changes to severe symptoms so quickly.

Prions are also dangerous because they’re more resilient than most microbes. Cooking temperatures don’t destroy prions like viruses or bacteria. Your immune system can’t stop prions, so there’s no way to develop an immunity to CJD or a vaccine to prevent it.

Types of CJD

Proteins can turn to prions in your body for multiple reasons. The different reasons are what determine the type of CJD you have. The different types are:

  • Sporadic CJD. This is the most common kind of CJD, making up about 85% to 90% of cases. It happens for unknown reasons.
  • Genetic CJD. This type happens because of a genetic mutation you inherit from one or both parents. It ranks second among the most common causes, making up between 10% and 15% of CJD cases.
  • Acquired CJD. This is CJD you “acquire” from various sources, such as medical procedures like organ or tissue transplants and grafts, contaminated surgical equipment, etc.
  • Variant CJD (vCJD). This happens after eating beef from a cow with bovine spongiform encephalopathy (BSE), another disease that happens because of prions. Prions that affect beef cattle with BSE can then pass it to humans and other species, causing vCJD.

Genetic CJD conditions

There are two specific genetic forms of CJD:

  • Gerstmann-Sträussler-Scheinker (GSS) syndrome. This condition is extremely rare and affects between 1 and 10 people out of every 100 million worldwide.
  • Fatal familial insomnia. This condition is even rarer than GSS syndrome. Researchers have only confirmed about two dozen cases.

Is CJD contagious?

CJD isn’t easily contagious from person-to-person contact. The only way to spread it from person to person is through organ or tissue transplants or certain types of hormones taken from a donor who had CJD.

Variant CJD can pass in blood transfusions, but this is extremely rare, and there are only four confirmed instances of this happening. Variant CJD is also extremely rare on its own. As of 2021, there had only been two cases of vCJD in the preceding five years (2016–2021). The last person with a confirmed case died in France in 2019.

Prion diseases in animals

Prions can cause similar conditions in different species of animals. BSE affects cattle, scrapie affects sheep and goats, and chronic wasting disease (CWD) affects deer, elk and related species. However, there’s currently no evidence that scrapie or CWD can affect humans.

While there’s no evidence that scrapie or CWD can cause Creutzfeldt-Jakob disease in humans, experts still recommend careful handling of both domestic animals and wild animals hunted for food because of the risk of a mutation that could allow a prion-caused condition to affect humans. Other diseases can also cause illnesses in humans. The U.S. Centers for Disease Control (CDC) and the U.S. Department of Agriculture both have more information about these topics and concerns.

Diagnosis and Tests

How is Creutzfeldt-Jakob disease diagnosed?

Your healthcare provider can diagnose CJD using a combination of methods, including:

  • Physical and neurological exams. These involve your healthcare provider looking for signs and symptoms of CJD and asking you to do certain tasks, which can help them identify problems with how your brain functions.
  • Diagnostic tests and imaging. These tests can measure your brain activity or create images of your brain structure.
  • Lab tests. These tests analyze blood or cerebrospinal fluid (a fluid that surrounds your brain and spinal cord) for signs of CJD, especially abnormal proteins and prions. This can also involve testing brain tissue directly after a person has died.

What tests will be done to diagnose this condition?

  • Brain MRI. This is the most likely — and most reliable — diagnostic imaging scan healthcare providers can use when diagnosing CJD.
  • Electroencephalogram (EEG). This test can help detect signs of unusual brain activity. While similar activity can happen with other conditions besides CJD, this test can still offer useful clues to healthcare providers as they work on a diagnosis.
  • Spinal tap (lumbar puncture). This test takes cerebrospinal fluid (CSF), which surrounds your brain and spinal cord, and analyzes it. High levels of certain proteins in your CSF can indicate a condition like CJD, and shaking a CSF sample under certain circumstances can cause changes that indicate a problem related to prions and proteins.
  • Brain biopsy. This test involves taking a sample of your brain tissue and analyzing it. A brain biopsy is the most definitive way to confirm CJD diagnosis. However, brain biopsies almost always happen after death, so they’re only good for confirming or ruling out a CJD diagnosis.
  • Genetic testing. Analyzing a sample of your blood or saliva can show if you have a genetic mutation that increases your chance of developing CJD.

Management and Treatment

How is Creutzfeldt-Jakob disease treated, and is there a cure?

Unfortunately, there’s no way to cure, treat or slow the progress of CJD. Your healthcare provider might recommend treating some of the symptoms, but this isn’t common because CJD often advances too quickly for treatments to help before the condition worsens.

How can I take care of myself or manage CJD symptoms?

CJD isn’t something you can self-diagnose, so it isn’t something you can treat or manage on your own. Many CJD symptoms can happen with other brain-related conditions, some of which are treatable or curable, making it important to get medical attention sooner rather than later if you have any symptoms of CJD.


How can I reduce my risk or prevent CJD?

Almost all cases of CJD are unpreventable, and there’s almost no way to reduce your risk of developing this condition. The one exception to this is variant CJD, which you can get from eating beef from a cow that had bovine spongiform encephalopathy.

Animal inspections help keep cattle with BSE out of the food supply in developed countries. However, animals that weren’t inspected or processed in a regulated facility could still pose a risk. Because of that, you should be very cautious about eating meat in developing areas or countries. In general, you should avoid meat from unregulated sources, especially brain tissue, bone marrow or products that contain either.

Animals that can carry other prion diseases

While there’s no evidence that scrapie or CWD can cause Creutzfeldt-Jakob disease in humans, experts still recommend careful handling of both domestic animals and wild animals hunted for food because of the risk of a mutation that could allow a prion-caused condition to affect humans.

Outlook / Prognosis

What can I expect if I have this condition?

Creutzfeldt-Jakob disease has a long latency period, which means you can contract it and have it for years before you show symptoms. Once symptoms start, it tends to worsen quickly, with different symptoms happening as the disease causes different areas of your brain to deteriorate.

In the early stages of the disease, people have changes in behavior and more mild symptoms, such as trouble with focusing and memory. As the condition gets worse, people with CJD lose the ability to take care of themselves and have trouble controlling their muscle movements. In the last stage of CJD, people stop talking, communicating and moving, with death following soon after.

How long does CJD last?

CJD is a permanent condition, and it usually causes a person’s death or at least is a contributing factor. Most cases of CJD are fatal within a few months to a year after diagnosis. The exception to this is genetic CJD, which can have a survival time of one to 10 years.

What is the outlook for this condition?

Unfortunately, CJD has a very poor outlook because the condition isn’t curable or treatable. It also worsens very quickly in most cases, causing death within weeks or months. Because this condition is so severe and gets worse so quickly, loved ones of a person with CJD should consider seeing a mental health professional — such as a counselor or therapist — to help them cope with the effects and changes that happen because of their loved one’s condition.

Living With

How do I take care of myself?

People with CJD typically need expert medical care within weeks or months of diagnosis. Because of that, it isn’t possible to take care of yourself if you have CJD. Your healthcare provider will usually recommend placing a person with CJD in a medical facility.

Additional Common Questions

How does a person get Creutzfeldt-Jakob disease?

The causes of CJD are as follows:

  • Sporadic (unknown cause): 85% and 90% of cases.
  • Genetic CJD (conditions inherited from one or both parents): 10% to 15% of cases.
  • Acquired CJD (infection from a medical procedure, such as a transplant or tissue graft): Less than 1% of cases.
  • Variant CJD (contracted by eating beef from an animal with bovine spongiform encephalopathy): Only 232 confirmed cases since 1986. The most recent person with variant CJD died in 2019.

Is Creutzfeldt-Jakob disease the same as mad cow disease?

Variant CJD (vCJD) happens because of bovine spongiform encephalopathy (BSE), better known as “mad cow disease.” However, there are only 232 total confirmed cases of this happening, the last of which involving a person who died in 1999. That means, more than 99% of CJD cases happen for reasons other than “mad cow disease.”

Can you survive Creutzfeldt-Jakob disease?

No, CJD is always fatal. That’s because your immune system can’t recognize the problem and can’t fight back against it as it can with other infectious diseases.


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