Jakob-Creutzfeldt disease is a degenerative brain disorder that affects humans and animals. It is also known as Creutzfeldt-Jakob disease, or simply CJD, and is caused by the build-up of abnormal prion proteins in the brain. The disease progresses rapidly and leads to neurological symptoms such as memory loss, confusion, and difficulty coordinating movements. Other synonyms for this disease include transmissible spongiform encephalopathy, prion disease, and mad cow disease. The latter is specifically related to the variant form of CJD that emerged in the 1990s in the United Kingdom, following the consumption of contaminated beef products. Regardless of its name, Jakob-Creutzfeldt disease remains a devastating disease with no known cure.