HOW HYPERTENSION AFFECTS MEMORY

Two out of three Americans age 60 and older have some form of high blood pressure -  which is blood pressure that measures 140/90 mm Hg or higher. Hypertension (the medical term for high blood pressure) affects Americans from all walks of life. Yet even though high blood pressure is easy to detect and is almost always treatable, too few people know that they have high blood pressure or even know much about it.

How does high blood pressure impact memory? The most obvious way is via stroke, which occurs when an artery supplying blood to a portion of the brain becomes blocked or suddenly ruptures.

Each year approximately 700,000 Americans suffer strokes, and many die because of them. Of those 500,000 who survive their first stroke, about 25 percent will have a second stroke within five years.

The damage to brain cells caused by a stroke can produce lasting disabilities that may impair a person's memory, senses, motor skills, behavior, language ability and thought processes. The specific deficits that occur depend on which portions of the brain are damaged, as well as the type and severity of the stroke.

Hypertension is a major risk factor for stroke. High blood pressure damages blood vessels that carry blood to the brain, and this damage leads to the buildup of arterial plaque, an accumulation of inflammatory cells, cholesterol and other tissue products within blood vessels. When one of these plaques ruptures, it travels through an artery and eventually gets lodged in a place where the diameter of the plaque is larger than the diameter of the blood vessels. This causes a blood clot to form at that spot.

If the clot completely cuts off blood supply to brain cells responsible for memory or other cognitive functions, the cells die. The death of these cells then leads to impairments in thinking, moving and sensing.

Having high blood pressure is also linked with greater declines in cognitive function when a stroke occurs. In a prospective, observational study, investigators tracked stroke incidence and cognitive performance among 9,704 women ages 65 and older. They found that among participants who had suffered strokes, those who had normal blood pressure before the stroke had better cognitive function afterward than those who were hypertensive beforehand.

(Source:  John Hopkins Health Alert,16 December 2013)