Extensive research of the recent years has demonstrated that piracetam is effective in the treatment of cognitive decline in aging and dementia. It is usually much more active in situations of impaired brain function. Accordingly, its mechanism of action has been associated with neurochemical deficits of the aged brain relevant to cognitive dysfunctions. Since many of these neurochemical deficits depend on changes of membrane properties, including fluidity, it is of special importance that piracetam not only modifies membrane properties by interacting with the polar head moieties of the phospholipid bilayer, but also that this effect is more pronounced in membranes of aged as opposed to young animal and human brains, and that this mechanism also has specific relevance for brain membranes of Alzheimer's disease patients. Altering membrane properties might also be involved in vascular effects of piracetam such as improved erythrocyte deformability and normalization of hyperactive platelet aggregation. This novel mechanism of piracetam thus combines a rather non-specific physico-chemical mode of action with the pharmacological and clinical experience with this unique drug - effects are always much more pronounced when function is impaired.