Abstract Hypertension is one of the principal risk factors for cerebrovascular diseases, closely correlated also with cognitive decline and dementia. Data from recent therapeutic trials (SYST-EUR, PROGRESS) open the way toward the prevention of dementia (vascular or Alzheimer's type) by antihypertensive treatments. The results of these two studies suggest different mechanisms of action of antihypertensive drugs in the prevention of cognitive decline. The use of angiotensin converting enzyme (ACE) inhibitors, with or without diuretics, resulted in decrease incidence of stroke-related dementia, but dementia without stroke was not reduced. With the dihydropyridine calcium antagonists, a reduction in both Alzheimer's type and vascular dementia was demonstrated.