Creutzfeldt-Jakob disease (CJD) is an extremely rare degenerative brain disorder (i.e., spongiform encephalopathy) characterized by sudden development of rapidly progressive neurological and neuromuscular symptoms. With symptom onset, affected individuals may develop confusion, depression, behavioral changes, impaired vision, and/or impaired coordination. As the disease progresses, there may be rapidly progressive deterioration of cognitive processes and memory (dementia), resulting in confusion and disorientation, impairment of memory control, personality disintegration, agitation, restlessness, and other symptoms and findings. Affected individuals also develop neuromuscular abnormalities such as muscle weakness and loss of muscle mass (wasting); irregular, rapid, shock-like muscle spasms (myoclonus); and/or relatively slow, involuntary, continual writhing movements (athetosis), particularly of the arms and legs. Later stages of the disease may include further loss of physical and intellectual functions, a state of unconsciousness (coma), and increased susceptibility to repeated infections of the respiratory tract (e.g., pneumonia). In many affected individuals, life-threatening complications may develop less than a year after the disorder becomes apparent.
In approximately 90 percent of cases, CJD appears to occur randomly for no apparent reason (sporadically). About 10 percent of affected individuals may have a hereditary predisposition for the disorder. Reports in the medical literature suggest that familial cases of CJD are consistent with an autosomal dominant mode of inheritance. In addition, in some extremely rare cases, CJD may take an infectious form. The disorder is thought to result from changes (mutations) in the gene that regulates the production of the human prion protein or direct contamination (transmission) with abnormal prion protein in infected brain tissue.
A variant form of CJD (V-CJD) has been reported in the United Kingdom that affects younger people (median age at onset: 28 years) than does classic CJD. In 1996, experts suggested the possibility that this variant might be associated with consumption of beef from cows with a related infectious brain disorder known as Bovine Spongiform Encephalopathy (BSE) or "Mad Cow Disease." BSE was first identified in the UK in 1986 and the number of reported cases grew rapidly, peaking in the winter of 1992-93 when almost 1,000 new cases were reported each week. Later, BSE also began to appear in some other European countries. Scientific research and debate continue concerning the potential link between BSE and V-CJD. In addition, coordinated national and international efforts are in place concerning the prevention, study, and surveillance of BSE and CJD. In early December 2000, European Union agriculture ministers agreed upon new measures to combat the spread of mad cow disease, including incinerating any cow over 30 months of age that had not tested negative for BSE. (BSE is thought to become detectable and infectious when cattle are approximately 30 months old.)