Creutzfeldt-Jakob Disease (CJD) is a rare, fatal brain disorder within a group of illnesses called prion diseases. The incidence of CJD cases worldwide is one to two cases, per million individuals, per year. In the United States this statistic translates to nearly 500 new cases per year. There is one CJD death per every 6,000 to 10,000 deaths in the U.S. each year.
Creutzfeldt-Jakob disease develops when a normal protein called cellular prion protein (PrPC) changes shape (misfolds) and becomes disease-causing prion. Prions slowly accumulate in the brain and usually cause tiny bubbles to form in brain cells, which gradually die. When enough brain cells malfunction or die, symptoms develop, followed by the person's death.
Sporadic CJD, the most common form, occurs at a rate of 1 or 2 new cases per million people each year throughout the world. It accounts for about 85% of cases. It usually affects people over 40 years old, usually around age 65. For this form, no cause is known.
Familial CJD results from a mutation in the gene for cellular prion protein, which causes normal cellular prion protein to change into disease-causing prion. It accounts for 5 to 15% of cases. Familial CJD is often inherited and usually starts at an earlier age and can last longer than sporadic CJD. Familial CJD is almost always inherited as an autosomal dominant disorder. That means that the mutation is not on the sex (X or Y) chromosomes and that only one mutated gene for the disease, one from either parent, is required for the disease to develop.
Acquired CJD can result from
Eating contaminated beef (called variant CJD)
Having had certain medical procedures when contaminated materials or instruments were unknowingly used (called iatrogenic CJD)
The most common early symptoms of Creutzfeldt-Jakob disease to occur is memory loss and confusion and loss of muscle coordination. In people with variant CJD, the first symptoms tend to be psychiatric symptoms (such as anxiety or depression), rather than memory loss.
Whether symptoms develop gradually or abruptly, mental function continues to deteriorate, often causing such symptoms as neglect of personal hygiene, listlessness, and irritability. Some people tire easily and become sleepy. Others cannot fall asleep.
Muscles usually begin to jerk involuntarily and quickly during the first 6 months after symptoms begin. Muscles may tremble, and people may become clumsy and uncoordinated. Walking becomes unsteady, resulting in staggering (similar to the walk of a person who is drunk). Movements may be slow. Muscles may jerk when stretched. Some people have hallucinations and seizures.
People may startle easily, and the resulting responses, such as jumping when a loud noise is heard, are exaggerated and often startling may trigger muscle jerking.
The muscles that control breathing and coughing are usually impaired, increasing the risk of pneumonia.
The symptoms worsen, usually much more rapidly than in Alzheimer disease, resulting in severe dementia.
Most people with CJD die within 6 to 12 months after symptoms appear. About 10 to 20% of people survive for a year or more.
Diagnosis of prion disease is challenging and is often made from clinical observation and the process of elimination of other diseases. The diagnosis of CJD can only be definitively confirmed through a brain biopsy or autopsy. Autopsy determines the type of prion disease and whether there is a genetic mutation. Key diagnostics for prion disease include electroencephalogram (EEG), brain MRI, and cerebral spinal fluid (CSF), with the Real-Time Quaking Induced Conversion (RT-QuIC) test, as well as tests for 14-3-3 and Tau proteins.
One of the most important parts of diagnosing prion disease, however, is ruling out other treatable conditions.
Currently, CJD cannot be cured, and its progress cannot be slowed. The disease is fatal, usually within months or a few years. However, certain medications may be given to relieve symptoms such as muscle jerking and anxiety.
Sources:
The CJD Foundation Inc.
National Institute of Neurological Disorders and Stroke
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