[Clinical trials in Alzheimer disease. Methodological problems: what application for what indication?]

For many years, all application dossiers sent to the Ministry of Health for use in Alzheimer's disease focused on the correction of cognitive disorders. Discussions were centered on the choice of cognitive evaluation scales and psychometric tests. The situation has since evolved and in addition to the cognitive disorders, applications must also consider daily life activities and comportmental disorders. Animal experiences remain classical, the use of aged animals not bringing much information and being extremely expensive. Phase I does not need to be modified at this stage. Phase II, however, must be done with extreme methodological rigor, and especially with an evaluation of pertinent clinical benefit in the cognitive and non-cognitive fields. The simple statistically significant improvement in one scale or another was not found sufficient by the Commission. The pharmaceutical company therefore has to find the benefit risk ratio that has real therapeutic interest. If this ratio seems pertinent to the Ministry, then phase III studies can be done to confirm longterm efficacy on enough patients. The study of drug action is very interesting to advance research or even in the application dossier, but in all cases, the ratio of pertinent clinical benefit to the risk of side effects remains the cornerstone of the decision.