Cerebral small vessel disease, cognitive impairment and vascular dementia.

In recent years, accumulating evidence has suggested that vascular risk factors (especially hypertension, and also diabetes, high level of cholesterol and smoking) contribute to Alzheimer disease. Vascular dementia had been traditionally considered secondary to stroke and vascular disease. However it appears that there is a continuous spectrum of disease, composed of a gradient of features of both types of dementia. The brain is an early target for organ damage due to high blood pressure. Hypertension is the major modifiable risk factor for stroke and small vessel disease and is known to be the most-important factor for macrovascular cerebral complications such as atherotrombotic stroke and, consequently, vascular dementia. Hypertension may also predispose to more subtle cerebral processes based on arteriolar narrowing or microvascular pathological changes. The term cerebral small vessel disease refers to a group of pathological processes with various etiologies that affect the small arteries, arterioles, venules, and capillaries of the brain. Age-related and hypertension-related small vessel diseases and cerebral amyloid angiopathy are the most common forms. It has been suggested that cerebral microvascular disease contributes to vascular cognitive impairment. The mechanisms underlying hypertension-related cognitive changes are complex and not yet fully understood. Both high and, especially in the elderly, low blood pressure have been linked to cognitive decline and dementia. There is some evidence that antihypertensive drug treatment could play a role in the prevention of cognitive impairment or vascular dementia through BP control. The BP levels that should be targeted to achieve optimal perfusion while preventing cognitive decline are still under debate.