{UAH} How Does Hypertension(high blood pressure) Affect Memory?
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[from Johns Hopkins HealthAlert email letter 20110117]
How Does Hypertension Affect Memory?
No matter which way you look at it, hypertension (high blood pressure) is bad for your brain. Hypertension is an important risk factor for cognitive impairment and Alzheimer's disease. And if you are diagnosed with Alzheimer's, hypertension may hasten cognitive decline.
What's more, hypertension is the most significant risk factor for strokes, which can lead to dementia by destroying brain tissue. This form of dementia, called vascular dementia, is the second most common type after Alzheimer's. It is most frequently caused by chronic hypertension, which can result in a series of small strokes. It is the accumulation of damage caused by multiple little strokes that commonly causes vascular dementia. Of course, hypertension can also cause a significant single stroke that can damage a large area of the brain and also cause dementia.
How does high blood pressure impact memory? The most obvious way is via stroke. High blood pressure damages blood vessels that carry blood to the brain, and this damage leads to the buildup of plaques, 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 that 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. About one third of people who suffer a stroke develop serious cognitive problems that interfere with their ability to perform daily activities.
Another way that blood pressure affects cognition is its effect on the white matter, the portion of the brain that lies below the surface. White matter is composed of nerve fibers that conduct messages between brain cells and a surrounding myelin sheath that acts as insulation and improves its function as a conduit of electrical and chemical information. Scans show that people with hypertension often have white matter abnormalities, probably because the hypertension produces impaired blood flow that starves nerve fibers of needed oxygen and nutrients. This causes the myelin sheath to decay and results in "demyelination," which shows up on magnetic resonance imaging (MRI) scans as bright white spots known as white matter hyperintensities (WMHs) or age-related white matter changes (ARWMCs).
Research shows that the greater the amount of white matter changes, the higher the risk of dementia. Reduced blood flow from hypertension can also directly affect cells in such areas of the brain as the hippocampus, which is involved in memory. When these cells do not get enough nutrients and oxygen, they cannot function properly. If this causes the death of cells, those areas of the brain may shrink. In addition, blood flow reduction leads to less efficient removal of waste product from brain tissue.
Last, hypertension may compromise the blood-brain barrier, a relatively impenetrable shield that surrounds the brain. This, in turn, allows toxic substances such as beta-amyloid (a sticky protein associated with Alzheimer's) to enter and accumulate in the brain.
From Dr. Peter V. Rabins, acclaimed author and geriatric psychiatrist at Johns Hopkins -- and one of the nation's leading experts on the care and management of patients with Alzheimer's.
--
*Abbey Kibirige Semuwemba*
Stalk my blog at: http://semuwemba.com/
"My journey is long and my preparation is so little, and weakness has gripped me and death is chasing me!"
-- How Does Hypertension Affect Memory?
No matter which way you look at it, hypertension (high blood pressure) is bad for your brain. Hypertension is an important risk factor for cognitive impairment and Alzheimer's disease. And if you are diagnosed with Alzheimer's, hypertension may hasten cognitive decline.
What's more, hypertension is the most significant risk factor for strokes, which can lead to dementia by destroying brain tissue. This form of dementia, called vascular dementia, is the second most common type after Alzheimer's. It is most frequently caused by chronic hypertension, which can result in a series of small strokes. It is the accumulation of damage caused by multiple little strokes that commonly causes vascular dementia. Of course, hypertension can also cause a significant single stroke that can damage a large area of the brain and also cause dementia.
How does high blood pressure impact memory? The most obvious way is via stroke. High blood pressure damages blood vessels that carry blood to the brain, and this damage leads to the buildup of plaques, 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 that 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. About one third of people who suffer a stroke develop serious cognitive problems that interfere with their ability to perform daily activities.
Another way that blood pressure affects cognition is its effect on the white matter, the portion of the brain that lies below the surface. White matter is composed of nerve fibers that conduct messages between brain cells and a surrounding myelin sheath that acts as insulation and improves its function as a conduit of electrical and chemical information. Scans show that people with hypertension often have white matter abnormalities, probably because the hypertension produces impaired blood flow that starves nerve fibers of needed oxygen and nutrients. This causes the myelin sheath to decay and results in "demyelination," which shows up on magnetic resonance imaging (MRI) scans as bright white spots known as white matter hyperintensities (WMHs) or age-related white matter changes (ARWMCs).
Research shows that the greater the amount of white matter changes, the higher the risk of dementia. Reduced blood flow from hypertension can also directly affect cells in such areas of the brain as the hippocampus, which is involved in memory. When these cells do not get enough nutrients and oxygen, they cannot function properly. If this causes the death of cells, those areas of the brain may shrink. In addition, blood flow reduction leads to less efficient removal of waste product from brain tissue.
Last, hypertension may compromise the blood-brain barrier, a relatively impenetrable shield that surrounds the brain. This, in turn, allows toxic substances such as beta-amyloid (a sticky protein associated with Alzheimer's) to enter and accumulate in the brain.
From Dr. Peter V. Rabins, acclaimed author and geriatric psychiatrist at Johns Hopkins -- and one of the nation's leading experts on the care and management of patients with Alzheimer's.
--
*Abbey Kibirige Semuwemba*
Stalk my blog at: http://semuwemba.com/
"My journey is long and my preparation is so little, and weakness has gripped me and death is chasing me!"
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