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Creutzfeldt-Jakob disease is a rare, rapidly progressing brain disease that is always fatal. However, as a diagnosis of exclusion, it can be misdiagnosed.

Creutzfeldt-Jakob (KROITS-felt YAH-kobe) disease, also known as CJD and classic Creutzfeldt-Jakob disease, is a rare degenerative disorder of the brain that occurs in about one in a million people every year. Rapidly progressing, CJD results in death in eight months to two years in most cases. There is currently no cure and no effective treatment, although there are medications to relieve the severity of symptoms.

What are the symptoms of CJD?

The story of former Defense Intelligence Agency case officer Richard McGhee is particularly well documented. McGhee had been diagnosed with an aggressive form of leukemia. He spent six months taking an experimental drug in a clinical trial at the MD Anderson Hospital in Houston, Texas. The cancer treatment was a complete success. He went into remission.

A couple of weeks after he got home from Houston, however, McGhee's family started noticing behaviors that were bizarrely out of character for him. He began writing odd notes he attached to the refrigerator door. One night his wife served something for dinner that he did not like, and he left a note on the table that she should not serve it again. 

The family shrugged off the odd behavior. They assumed he was worn out from his cancer treatment. And McGhee was wanting to sleep all the time. But McGhee's symptoms got worse.

Richard began to confuse day and night. He couldn't remember why he went into a room or whether he had just eaten. "He was acting like a two-year-old," his daughter Melissa reported. But within a few more weeks, he could stand up unassisted.

Richard McGhee showed the classic symptoms of CJD. But it turned out he actually had Lyme disease. He received appropriate treatment and made a full recovery. Richard is a good example of why it is important not to rush a diagnosis of CJD.

The diagnostic criteria for CJD are rapid cognitive decline plus at least two of the following:

  • Myoclonic (sudden) muscle movements, either sudden contractions or sudden loss of muscle tone.
  • Cerebellar symptoms, such as not being able to stand up unassisted.
  • Akinetic mutism, a tendency neither to move nor to speak.
  • Pyramidal and/or extrapyramidal symptoms, such as a loss of fine movements, hyperactive reflexes, and an increase in muscle tone in the lower legs and feet.
  • Visual symptoms.
  • Other signs of damage to the cortex, such as the loss of an ability to understand language or uncoordinated movements.

In addition to these symptoms, there must be a normal EEG and normal MRI and no other cause found. If the patient can withstand a "spinal tap" (lumbar puncture), spinal fluid can be analyzed with the real-time quaking-induced conversion (RT-QuIC) test, which is extremely accurate for confirming the presence of prions.

What other diseases can be mistaken for CJD? Similar symptoms can be caused by Lyme disease (as for Richard McGhee, mentioned above), herpes infections of the brain, chemotherapy for cancer, lithium poisoning, and Lewy body disease, among others.

What causes CJD?

Creutzfeldt-Jakob disease is a type of prion disease. This is a group of diseases that includes:

  • Bovine spongiform encephalopathy — BSE or "mad cow disease" (cattle)
  • Chronic wasting disease or CWD (mule deer and elk)
  • Scrapie (sheep)
  • Gerstmann-Sträussler-Scheinker disease (humans)

 All of these diseases "incubate" over many years but result in rapid deterioration once symptoms appear. The causative agent in these diseases is a malformed protein in the brain. These prions are  a kind of glycoprotein, a chemical combination of glucose and amino acids, that are a mirror image of the functional molecule. The glycoprotein that is misshaped in prion diseases helps the brain use copper as a nutrient.

Prion diseases are unusual in that there is more than one way that prions can get into the brain. It is possible to inherit a gene that codes the production of the glycoprotein incorrectly. CJD can be an inherited disease. It is also possible to have a mutation in the gene that codes the production of the protein after birth. And it is possible to become "infected" with prions after medical procedures or from eating the brains of animals (or humans, in the case of another prion disease called kuru) that are infected with prions. Despite what you may have seen on the television program The X Files, the overwhelming majority of cases of CJD result from spontaneous mutations of the genes that code the problem glycoprotein. Most cases of CJD have nothing to do with eating brains, or with genes you inherit from your parents.

What are the types of CJD?

The kind of CJD we hear the most about is variant CJD, also known as vCJD. This is a prion disease that could be caused by consuming the brain of a "mad dow" or a deer that had chronic wasting disease. Very few people get this kind of CJD because the proteins affected by the disease are slightly different in different species. You can't, for example, get CJD from a mouse. However, about 7.5 percent of cases of CJD are vCJD.

The kind of CJD that is inherited in families is known as familial CJD. There are small ethnic groups that have rates of CJD from 60 to 100 times greater than expected. These include Libyan Jews and some towns in Slovakia. This form of CJD accounts for another 7.5 percent of cases.

About 85 percent of all cases of CJD are "sporadic." They are the result of a mutation of a gene after birth. And a small number of cases are iatrogenic CJD, resulting from the implantation of an infected electrode into the brain or exposure to brain matter from an infected person during an autopsy.

Death usually comes in about eight months in sporadic CJD. Some people who develop symptoms of vCJD live about two years. Familial CJD usually ends in death in about 14 months.

Treatment for CJD

The only treatments for CJD that are currently available are intended to relieve symptoms, such as seizures and muscle pain. Gene therapies are under development, but right now it is only possible to reduce suffering during the inevitable course of the disease.

  • Geschwind MD, Murray K. Differential diagnosis with other rapid progressive dementias in human prion diseases. Handb Clin Neurol. 2018.153:371-397. doi: 10.1016/B978-0-444-63945-5.00020-9. Review. PMID: 29887146.
  • Masters CL, Harris JO, Gajdusek DC, Gibbs CJ Jr, Bernoulli C, Asher DM. Creutzfeldt-Jakob disease: patterns of worldwide occurrence and the significance of familial and sporadic clustering. Ann Neurol. 1979 Feb. 5(2):177-88.
  • Meiner Z, Halimi M, Polakiewicz RD, Prusiner SB, Gabizon R. Presence of prion protein in peripheral tissues of Libyan Jews with Creutzfeldt-Jakob disease. Neurology. 1992 Jul. 42(7):1355-60.
  • Photo courtesy of SteadyHealth

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