Creutzfeldt-Jakob disease (CJD) is a rare, fatal neurodegenerative condition. It causes rapidly progressing dementia, leading to swift decline in cognitive function and motor control. It affects about one in a million people worldwide annually. CJD differs from common dementias due to its unique cause and swift progression.
The Nature of Prion Disease
Creutzfeldt-Jakob disease is a prion disease. Unlike bacterial or viral infections, prion diseases are caused by abnormal forms of naturally occurring proteins called prions. A prion is a misfolded version of a normal brain protein (PrP-sen) that becomes the disease-causing form (PrP-res).
Prions induce normal proteins to misfold. This process resembles a chain reaction, like falling dominoes. A prion acts as a template, causing healthy proteins to adopt the pathological conformation. This leads to abnormal prion accumulation within brain cells. These aggregates damage neurons, creating microscopic holes that give brain tissue a sponge-like appearance.
Forms and Transmission of CJD
Creutzfeldt-Jakob disease has several forms, each with a distinct origin but similar brain damage. Sporadic CJD is the most prevalent type, accounting for about 85% of cases. It arises spontaneously without known cause or risk factor, typically affecting individuals aged 60 to 70. Its occurrence is unpredictable, likely from a random misfolding event of normal prion protein.
Hereditary CJD accounts for 10% to 15% of cases. It links to an inherited genetic mutation in the PRNP gene, which instructs normal prion protein production. This mutation predisposes prion proteins to misfold, leading to disease development later in life. Family history is often key to identifying this form.
Acquired CJD is the least common, resulting from external exposure to abnormal prions. Iatrogenic transmission, through accidental medical or surgical procedures, is one pathway. Examples include contaminated neurosurgical instruments, corneal transplants, or dura mater grafts. Historically, some cases linked to contaminated human growth hormone before synthetic alternatives.
Variant CJD (vCJD) gained public attention due to its link with Bovine Spongiform Encephalopathy (BSE), or “mad cow disease.” It is primarily transmitted through consuming beef products from BSE-infected cattle. Unlike other forms, vCJD affects younger individuals and has a longer illness duration. This connection highlights how prions can cross species barriers.
Symptoms and Progression
CJD symptoms emerge rapidly and worsen quickly. Early signs include memory impairment, personality shifts, and coordination difficulties (ataxia). Patients may experience confusion, disorientation, and trouble with judgment, resembling other dementias. These initial signs can be mistaken for common neurological conditions, making early differentiation challenging.
As the disease progresses, decline is swift, distinguishing CJD from gradual neurodegenerative conditions like Alzheimer’s. Within weeks to months, patients develop severe neurological deficits. Involuntary muscle jerks (myoclonus) become prominent. Visual disturbances, including blurred vision or blindness, are common.
Rapid deterioration leads to profound motor control loss, making walking and standing impossible. Speech diminishes, often progressing to mutism. In final stages, patients become severely cognitively and physically incapacitated, completely dependent on care. Death typically occurs within one year of symptom onset, often within six months.
Diagnosis and Management
Diagnosing CJD in a living person is challenging, as no single definitive test exists. Doctors rely on clinical signs and specialized investigations for a probable diagnosis. Brain MRI scans can reveal characteristic abnormalities, especially in specific regions. Electroencephalogram (EEG) recordings may show distinctive abnormal brain wave patterns.
Cerebrospinal fluid (CSF) analysis, obtained via lumbar puncture, is also used. Tests like Real-Time Quaking-Induced Conversion (RT-QuIC) detect misfolded prion proteins in CSF with high sensitivity, aiding probable diagnosis. Despite these tests, definitive CJD diagnosis requires post-mortem brain tissue examination. This involves microscopic analysis to identify sponge-like changes and abnormal prion proteins.
No cure or effective treatment exists for CJD. Medical care focuses on palliative measures, managing symptoms and providing comfort. Medications may alleviate pain, reduce agitation, or control muscle jerks (myoclonus). Supportive care ensures proper nutrition, hydration, and hygiene, enhancing quality of life for the illness’s brief duration.
References
The National Institute of Neurological Disorders and Stroke. Creutzfeldt-Jakob Disease Fact Sheet. (n.d.).
Centers for Disease Control and Prevention. About Prion Diseases. (2021, March 24).
National Institute of Neurological Disorders and Stroke. Creutzfeldt-Jakob Disease. (n.d.).
Mayo Clinic. Creutzfeldt-Jakob Disease. (2024, May 18).
Centers for Disease Control and Prevention. Creutzfeldt-Jakob Disease, Classic (CJD) | Types of CJD. (n.d.).
World Health Organization. Variant Creutzfeldt-Jakob Disease (vCJD). (n.d.).
National Institute of Neurological Disorders and Stroke. Creutzfeldt-Jakob Disease Fact Sheet. (n.d.).
Mayo Clinic. Creutzfeldt-Jakob Disease. (2024, May 18).
Centers for Disease Control and Prevention. Creutzfeldt-Jakob Disease, Classic (CJD) | Diagnostic Tests. (n.d.).