The goal of this research is to improve the informations about the role of same environmental factors, expecially regarding occupational activity, on the pathogenesis of Alzheimer desease. An epidemiologic design was prepared, retrospective about occupational exposure to risk factors, and also with a low number of subjects under study, it permits to find a correlation between risk factors and desease. This case-control study foresee the recruiting of 500 patients with Alzheimer desease, like the NINCDS-ADRDA criteria, and 500 controls. On a selected group of subjects is applyed a chelation test with calcium versenate, to observe possible alterations of body levels of toxic or essential elements. This analysis will be applyed both on patients with Alzheimer desease than on healthy rappresentative sample, trying to find a priori who was occupationally exposed to risk factors.