Creutzfeldt-Jakob disease. Coloured magnetic resonance imaging (MRI) scan of an axial section through the brain of a 35-year-old patient, showing hyperintensity in the region of the cerebral cortex. These are typical radiological signs indicative of the presence of Creutzfeldt-Jakob disease (CJD). CJD is the result of virus-like prions within the brain that cause vacuoles and plaques to form, making the brain spongy and killing off the tissue. Symptoms include dementia and sudden muscle contractions, leading to death. The similarly fatal cattle disease BSE (bovine spongiform encephalopathy) has now been linked to human CJD.