A disease of the neurological system caused by a PRION. Spongy degeneration of the BRAIN occurs with progressive DEMENTIA. Known examples of the disorder in humans are CREUTZFELDT-JAKOB DISEASE (CJD) and KURU. Among animals, scrapie in sheep and BOVINE SPONGIFORM ENCEPHALOPATHY (BSE) are similarly caused. The latter has occurred as an outbreak in cattle over the past decade or so, probably as a result of cattle being fed processed offal from infected animals. Some people have developed a variant form of CJD from eating infected beef.