Creutzfeldt-Jakob disease (CJD) is a rare, degenerative, and fatal brain disorder, and only one individual in a million contracts the disease worldwide. Most victims are around sixty years old when they start showing symptoms, and most die within a year. Creutzfeldt-Jakob disease belongs to a family of diseases called prion diseases or transmissible spongiform encephalopathies (TSEs). A prion is a misshapen protein that causes degenerative diseases of the brain in humans and animals. 'Spongiform' describes the characteristic look of affected brains: the prions eat holes in them until they resemble sponges.
There are three main types of Creutzfeldt-Jakob disease. Sporadic CJD has no known cause and is by far the most common, affecting about eighty-five percent of patients. Familial Creutzfeldt-Jakob disease runs in families and is caused by mutated genes that can be identified through tests. Acquired CJD is caused by exposure to affected tissue from the brain or nervous system.
The early symptoms will depend on the type of Creutzfeldt-Jakob disease. A patient with sporadic or familial CJD will develop neurological symptoms first, including difficulty walking, which is caused by decreased coordination and balance. This will often mean increased stumbling and unsteadiness. Patients will often require assistance to be able to walk.
As the disease progresses, the patient will often develop involuntary spasms of different muscles (myoclonus). While patients with variant Creutzfeldt-Jakob disease, caused by eating meat from a cow with 'mad cow'; disease, will develop psychological symptoms first, they will develop the neurological symptoms like difficulty walking, about four months later.