Several drug candidates with potential preventive effects have already been explored with little success (statins, antihypertensives, NSAIDs, aspirin, steroid hormones). Other studies have suggested the existence of deleterious cognitive effects of certain substances (benzodiazepines, anticholinergics, anti-cancer chemotherapy). However, only the effects of a limited number of drugs were analyzed, and most drugs have not been specific study in epidemiology.