Diseases and Disorders

Prion Diseases: Creutzfeldt-Jakob Disease

Yash Kilam


Introduction

Creutzfeldt-Jakob Disease (CJD) is the most common of a rare group of neurodegenerative pathogens known as human prion diseases [7]. Many researchers believe these diseases are caused by the development of abnormal bundles of proteins found on the surface of brain cells, called prions [5]. Despite being the most common form of a human prion disease, there are only an estimated 350 cases of Creutzfeldt-Jakob in the US per year [1].  Unfortunately, the disease has no known cure and is fatal, leaving most patients dead after anywhere from 4 months to 2 years following their first symptoms [6]. This article aims to look into the causes, details on diagnosis, symptoms, and treatments for CJD.
 

History

The disease was first discovered in the 1920s by German neurologists, Hans Gerhard Creutzfeldt and Alfons Maria Jakob [12]. CJD captured the public’s attention in the 1990s when individuals in the United Kingdom developed a variant of Creutzfeldt-Jakob disease, vCJD,  upon eating meat from diseased cattle. However, the non-variant form of CJD has not yet been linked to infected beef [3].

 

Causes and Transmission

CJD is a rapidly progressive and invariably fatal condition [2]. The prion proteins behind it are misfolded isoforms of cellular glycoproteins which come together to become a singular particle: a prion [2]. There are three forms of CJD which one can contract: (i) Sporadic; (ii) Familial; and (iii) Acquired [4]. Sporadic CJD has no known cause and can occur naturally in anyone [4]. It represents over 85% of all cases of CJD and usually affects those above the age of 40 [6]. Familial CJD occurs when a mutation in the PRNP gene for the PrPC protein causes normal PrPC to change into a disease-causing prion [9]. It accounts for 5 to 15% of cases and occurs at a younger age than the sporadic form [6]. Acquired CJD happens when one comes in contact with infected material/tissue [4]. No confirmed cases of Acquired CJD have been previously reported [6].

 

Diagnosis

The only method to confirm a diagnosis of CJD is by performing a brain biopsy, which is very risky to execute while the patient is still alive [9]. If trying to narrow down the list of possibilities, a neurologist would start by carrying out a series of tests to make sure it isn’t misdiagnosed as a condition with similar symptoms, such as a brain tumor, Parkinson’s, or Alzheimer’s [10]. These tests may include an MRI brain scan, an EEG, a prototype blood test, a tonsil biopsy, or a genetic test [10]. Another examination involves a lumbar puncture, which can test spinal fluid to rule out other causes of dementia (a symptom of CJD) [9]. It can also show if there is an infection or increased pressure in the central nervous system [9]. If detectable 14-3-3 proteins are leaking into the spinal fluid, a sign of rapid neuronal degeneration, there is an increased chance that the person has CJD [9]. During a brain biopsy, a surgeon drills a tiny hole into the skull and removes a small piece of brain tissue using a very thin needle [10]. It is performed under general anesthetic, meaning that the patient will be unconscious during the procedure [10]. Since a brain biopsy carries the risk of causing seizures, it is only performed in a small number of cases when there is no concern that someone may  have CJD but rather, some other treatable condition [10].

 

Symptoms

Creutzfeldt-Jakob disease is marked by rapid mental deterioration, usually within a few months [3]. Symptoms include personality changes, anxiety, depression, dementia, impaired thinking, blurred vision or blindness, insomnia, difficulty speaking, difficulty swallowing, and sudden jerking movements [3]. As the disease progresses over time, the patient’s mental symptoms will worsen [9]. Most infected individuals will eventually go into a coma [9]. Heart and respiratory failure, pneumonia or other infections are generally the cause of death in CJD infected people [3]. For those with the rarer vCJD, psychiatric symptoms may be more prominent in the beginning, with dementia developing later in the illness [3].

 

Treatments

There is no treatment that can slow or stop the neuronal destruction caused by Creutzfeldt-Jakob disease and other prion diseases [7]. Many drugs have been tested, including acyclovir, amantadine, antibiotics, antiviral agents, interferon and steroids, although none have shown positive results [8]. Currently, the treatment for CJD aims to ease symptoms and make the person as comfortable as possible [1]. The drugs clonazepam and sodium valproate may help relieve myoclonus [8]. Muscle stiffness and twitching may be treated with muscle-relaxing medications or antiepileptic drugs [7]. In the later stages of the disease, individuals with Creutzfeldt-Jakob disease will become completely dependent on others for their daily needs and comfort [7]. As of now, researchers at the UCSF Memory and Aging Center are trying to identify compounds for a treatment or a cure for CJD and other diseases caused by infectious prions [8].

 

Glossary


References


  1. NINDS. (13/8/2019). Creutzfeldt-Jakob Disease Fact Sheet. National Institute of Health. https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-sheets/Creutzfeldt-Jakob-Disease-Fact-Sheet. Retrieved: 12/20/19.

  2. CDC. (9/10/2018). Creutzfeldt-Jakob Disease, Classic (CJD). Center for Disease Control and Prevention. https://www.cdc.gov/prions/cjd/index.html. Retrieved: 12/20/19.

  3. Mayo Clinic. (4/10/2018). Creutzfeldt-Jakob Disease. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/creutzfeldt-jakob-disease/symptoms-causes/syc-20371226. Retrieved: 12/22/19

  4. Medline Plus. (8/5/2019). Creutzfeldt-Jakob Disease. Medline Plus. https://medlineplus.gov/creutzfeldtjakobdisease.html. Retrieved: 12/22/19

  5. Stanford Health Care. Creautzfeldt-Jakob disease(prion disease). Stanford Health Care Organization. https://stanfordhealthcare.org/medical-conditions/brain-and-nerves/dementia/types/prion-disease.html. Retrieved: 12/22/19

  6. Gambetti, Pierluigi. Creutzfeldt-Jakob Disease (CJD) (Subacute Spongiform Encephalopathy). Merck Manuals. https://www.merckmanuals.com/home/brain,-spinal-cord,-and-nerve-disorders/prion-diseases/creutzfeldt-jakob-disease-cjd. Retrieved: 12/22/19

  7. Alzheimer’s Association. Creutzfeldt-Jakob Disease. Alzheimer’s Association. https://www.alz.org/alzheimers-dementia/what-is-dementia/types-of-dementia/creutzfeldt-jakob-disease. Retrieved: 12/23/19

  8. UCSF Health. Creutzfeldt-Jakob Disease Treatments. UCSF Health Organization. https://www.ucsfhealth.org/conditions/creutzfeldt-jakob-disease/treatment. Retrieved: 12/23/19

  9. Kraft, Sy. (26/4/2019). What Is Creutzfeldt-Jakob Disease? Medical News Today. https://www.medicalnewstoday.com/articles/185884.php. Retrieved: 12/24/19

  10. NHS. (14/6/2018). Diagnosis of Creutzfeldt-Jakob Disease. NHS UK. https://www.nhs.uk/conditions/creutzfeldt-jakob-disease-cjd/diagnosis/. Retrieved: 12/24/19

Yash Kilam

Yash Kilam


A passionate, responsible and aspiring neuroscience student seeking opportunities to write and research on neuroscience. I am especially interested in learning more about neurological disorders and how they arise. In the future, I want to research more about consciousness and the different types of brain cells.