From the Encyclopedia
Creutzfeldt-Jakob disease (CJD) is the most common human form of a group of rare, fatal brain disorders known as prion diseases.
Creutzfeldt-Jakob disease progresses rapidly. Creutzfeldt-Jakob disease causes a type of dementia that gets worse unusually fast. More common causes of dementia, such as Alzheimer’s, dementia with Lewy bodies and frontotemporal dementia, typically progress more slowly.
Prion diseases, such as Creutzfeldt-Jakob disease, occur when prion protein, which is found throughout the body but whose normal function isn’t yet known, begins folding into an abnormal three-dimensional shape. This shape change gradually triggers prion protein in the brain to fold into the same abnormal shape.
Through a process scientists don’t yet understand, misfolded prion protein destroys brain cells. Resulting damage leads to rapid decline in thinking and reasoning as well as involuntary muscle movements, confusion, difficulty walking and mood changes.
CJD is rare, occurring in about one in 1 million people annually worldwide. Experts generally recognize the following main types of CJD:
Sporadic CJD develops spontaneously for no known reason. It accounts for 85 percent of cases. On average, sporadic CJD first appears between ages 60 and 65.
Familial CJD is a heredity form caused by certain changes in the prion protein gene. These genetic changes are “dominant,” meaning that anyone who inherits a CJD gene from an affected parent will also develop the disorder. Familial CJD accounts for about 10 to 15 percent of cases.
Acquired CJD results from exposure to an external source of abnormal prion protein. These sources estimated to account for about 1 percent of CJD cases.
The two most common outside sources are:
1) Medical procedures involving instruments used in neurosurgery, and;
2) growth hormone from human sources or certain transplanted human tissues.
The risk of CJD from medical procedures has been greatly reduced by improved sterilization techniques, new single-use instruments and synthetic sources of growth hormone.