Arterial hypertension may be responsible for cognitive impairment indirectly, by means of ischemic or haemorrhagic cerebral lesions. In this regard multi-infarct dementia, subcortical dementia due to "small vessel disease" and Binswanger's syndrome are the clinical pictures more commonly observed. However also in hypertensives free from cerebrovascular events, dysfunctions in memory, attention, abstract reasoning, mental flexibility and psychomotor abilities have been found. The pathogenesis of these findings is uncertain. Small cerebral asymptomatic lesions (lacunae, leukoaraiosis) could disconnect the cortical and subcortical structures in the brain; however other factors, such as global or regional reductions of cerebral blood flow or disturbances in neurotransmitters release cannot be ruled out. The effects of anti-hypertensive therapy are conflicting, some authors reporting an improvement and others a worsening of cognitive performances. In the elderly the risk linked to hypertension may be increased by several predisposing factors and therefore this condition must be considered with attention as a pathogenetic factor of senile dementia.