The frame of neurodegenerative diseases contains multiple pathologies for which very few active drugs have been found. Currently, drugs whose benefit is well established, are only available for Alzheimer's disease. May we term these drugs anti-dementia drugs? Pharmacological research was first oriented to find the mythic Fontaine of Youth. Nowadays, it is directed in a more concrete way, to protect the neurone from aggression before the occurrence of dementia. This pledge could appear very hazardous because we do not know the nature of the aggressors, and time is associated with wearing out and decline. Neurosciences have shown that there is a biology of cognition and that neurogenesis and apoptosis are permanently in confrontation in the brain. The present targets of pharmacology are directed against the decline of the neurone and of cognitive performance. Clinicians will check the accuracy of this very ambitious project.