[Creutzfeldt-Jakob disease in patients before and after 80 years of age].

The frequency of sporadic CJD is maximum in the 70 to 79 years age group and decreases later. Clinical signs of CJD after the age of 80 do not differ from those before 80 excepted for myoclonia and cerebellar symptoms that are less frequently observed. The results of surrogate markers, neuropathological and biochemical examinations are comparable before or after 80 years old. This last result suggests that the causal event of the disease, potentially the conversion of PrP(c) into PrP(sc), is not qualitatively regulated by brain aging.