Creutzfeldt-Jakob Disease (CJD)

What Is It?

Creutzfeldt-Jakob disease (CJD) is a rare, fatal brain disorder associated with the presence of a misshapen protein in the brain, known as a prion. Although prion-associated diseases are not well understood, scientists theorize that prions cause damage by causing healthy proteins in the brain to take the prion shape, so these too become damaging particles. This slow chain-reaction of damaged proteins occurs over many years and results in brain damage.

When symptoms appear, CJD causes rapidly progressive dementia (mental decline) and involuntary jerking muscle movements called myoclonus. About 90 percent of those affected die within one year of diagnosis.

Because contamination by prion particles can spread this disease, it is considered an infectious illness. However, prions do not move easily from one person to another. Most cases of CJD are not caused by exposure to another person with the disease but rather by an accidental mutation in brain-cell DNA that allows a prion particle to be formed. This mutation can be sporadic (occurring for the first time in a family, without family history of the same gene mutation and disease) or hereditary (passed down from parent to child). Most cases of CJD are sporadic. Between 5 percent and 15 percent are caused by inheritance of the gene mutation that encodes the prion protein. Czechoslovakian-, Chilean- and Libyan-born Jews have a higher-than-average number of inherited cases of CJD. Because the effects occur very slowly, inherited CJD does not cause symptoms until adulthood.

It is extremely uncommon for this disease to spread from one person to another, but during medical procedures, it can spread on contaminated equipment, such as surgical instruments and brain electrodes, or contaminated tissue, such as corneal transplants, natural human growth hormone and human gonadotropins for treatment of infertility. In Britain, a small number of cases of CJD have recently been linked to the consumption of beef from cattle infected with bovine spongiform encephalopathy, or mad cow disease.

Symptoms

CJD does not cause any symptoms at first. The first symptoms to appear include slow thinking, difficulty concentrating, impaired judgment, memory loss, personality and behavioral changes, and difficulties with coordination and vision. These symptoms rapidly give way to increasing mental deficits leading to severe, progressive dementia (mental decline) associated with self-neglect, apathy or irritability, and prominent muscle spasms (myoclonus). As the disease progresses, seizures commonly occur. Symptoms continue to worsen until both mental and physical functions are lost; patients are completely bedridden, and eventually lapse into coma. Comatose patients may die as a result of infection associated with being immobile, such as pneumonia.

Diagnosis