Creutzfeldt-Jakob (KROITS-felt YAH-kobe) disease (CJD) also known as Mad Cow Disease is a degenerative brain disorder that leads to dementia and, ultimately, death. Creutzfeldt-Jakob disease symptoms can be similar to those of other dementia-like brain disorders, such as Alzheimer’s disease. But Creutzfeldt-Jakob disease usually progresses much more rapidly.

CJD captured public attention in the 1990s when some people in the United Kingdom developed a form of the disease — variant CJD (vCJD) — after eating meat from diseased cattle. However, “classic” Creutzfeldt-Jakob disease hasn’t been linked to contaminated beef. All types of CJD are serious, but very rare. Worldwide, about one to two cases of CJD are diagnosed per million people each year, most often in older adults.