The review summarizes the current views on the pathogenesis of dementia and the significance of blood pressure levels for its development. The present status of the prevention of cognitive disorders and dementia is detailed in the use of antihypertensive therapy: there are the data of prospective cohort studies of the impact of antihypertensive therapy on the risk of dementia, the results of placebo-controlled studies in the groups of elderly and senile patients with a history of cerebrovascular complications, and the data of meta-analyses of studies. As for cognitive function, the effects of different classes of the currently available antihypertensive agents, such as diuretics, calcium antagonists, angiotensin-converting enzyme inhibitors, and angiotensin II type 1 receptor antagonists, are analyzed.