Brain renin-angiotensin system in cognitive function: pre-clinical findings and implications for prevention and treatment of dementia.

Biochemical, physiological and functional studies suggest that the brain renin-angiotensin system (RAS) is regulated independently of the peripheral RAS. Also, all enzymes and peptides necessary for the biosynthesis of various angiotensins have been recognized within the central nervous system. There are divergent opinions concerning the localization of the different components of this system which is not fully understood. It is believed that central actions of angiotensins are not exclusively associated with their traditional roles, many studies showing that central angiotensins are also involved in learning and memory processes. Moreover, clinical trials and studies on animal models suggest that pharmacological manipulation of angiotensin ligands may be of clinical importance in slowing or even stopping the cognitive deterioration seen in vascular dementia and Alzheimer's disease.