Creutzfeldt-Jakob disease (CJD) is the most common human form of a group of rare, fatal brain disorders known as prion disease. Prion is a protein that is normally found in our body but its exact function is not yet known.
Prion diseases, such as Creutzfeldt-Jakob disease, occur when prion protein begins folding into an abnormal three-dimensional shape. This distortion of shape gradually triggers prion protein in the brain to fold into the same irregular shape. The distorted prion protein destroys brain cells and the resulting damages lead to a rapid decline in thinking and reasoning as well as involuntary muscle movements, confusion, difficulty walking and mood changes.
Creutzfeldt-Jakob disease (CJD) is rare, occurring one person for every one million people each year around the world. The following main types of CJD have been recognized:
- Sporadic CJD develops spontaneously for no known reason. It accounts for 85 per cent of cases and appears between ages 60 and 65.
- Familial CJD is a hereditary form caused by certain changes in the prion protein gene. These genetic changes are mostly inherited so that a person who inherits a CJD gene from an affected parent will also develop the disorder. Familial CJD accounts for about 10 to 15 per cent of cases.
- Infectious CJD is an especially rare form of CJD and results from exposure to an external source of abnormal prion protein. These sources are only estimated to account for about one per cent of CJD cases.
What are the symptoms?
Symptoms of Creutzfeldt-Jakob disease and the order in which they appear can vary significantly from person to person. Common symptoms include:
- Rapidly worsening confusion, disorientation, and problems with memory, thinking, planning and judgment
- Agitation, apathy and mood swings
- Difficulty walking
- Muscle stiffness, twitches and involuntary jerky movements.
Causes and risks
We do not yet know the cause of sporadic Creutzfeldt-Jakob disease. It is believed that the disease begins when prion protein somewhere in the brain spontaneously misfolds, triggering the misfolding of prion protein throughout the brain. Genetic abnormalities in the prion protein gene may affect the risk of this spontaneous misfolding.
Familial CJD is caused by irregularities in the prion protein gene. Researchers have identified more than 50 prion protein mutations in those with inherited CJD. Genetic testing can determine whether family members are at risk.
How is it diagnosed?
Creutzfeldt-Jakob disease is a very rare cause of dementia. One of its common characteristics is the rapid progression of symptoms. There is no single test (or any combination of tests) that can conclusively diagnose sporadic CJD, but the following tests may help determine whether an individual has CJD:
- Electroencephalogram (EEG) measures the brain's patterns of electrical activity
- Brain magnetic resonance imaging (MRI) can detect certain brain changes consistent with CJD.
- Lumbar puncture (spinal tap) tests spinal fluid for the presence of certain proteins.
What kind of treatment is available?
Currently, there is no treatment that can slow or stop the underlying brain cell damage caused by Creutzfeldt-Jakob disease and other prion diseases. Various pharmaceutical drugs have been tested but have not shown any conclusively benefit. Clinical studies of potential CJD treatments are complicated by the rarity of the disease and its rapid progression.
Current therapies focus on treating and managing symptoms through the use of painkillers such as opiates to control pain and muscle relaxants or anti-seizure drugs to reduce stiffness and twitching. In the latter stages of the disease, individuals with CJD become dependent on others for their daily needs and comfort.
CJD progresses rapidly. The rate of progression of the disease and the average life span following diagnosis can vary from person to person. People affected eventually lose their ability to move or speak and require full-time care to meet their daily needs. The life span for an estimated 90% of people diagnosed will be approximately one year. Those affected by familial CJD tend to develop the disorder at an earlier age and survive longer than those with the sporadic form.
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