Creutzfeldt-Jakob Disease was discovered in 1920 and is relatively rare: there are 1.4 cases per million people per year i.e.a total of 80 to 90 cases per year in France. It is a prion encephalopathy that (in its classical form) affects adults between 50 and 75 years old.
It begins with psychological problems rapidly progressing to dementia. Symptoms include loss of reasoning ability, deterioration in memory, speech disorders and uncontrolled movements.
A new variant of Creutzfeldt-Jakob disease has emerged since 1996. This affects younger people and is derived from bovine spongiform encephalopathy (Mad Cow Disease). It may be contracted by eating meat from sick cattle.