High blood pressure and decreased blood flow inside the brain can stimulate the accumulation of harmful plaque and signal the start of dementia, researchers found the University of South Carolina.
"If you have problems with the blood vessels in the brain, there is a risk of difficulties associated with thinking and memory, and eventually it will lead to other pathologies of the brain , such as Alzheimer's disease," - said Daniel Nation, lead author of the study. Nation defined a new method of calculating the cerebral vascular resistance arising due to high blood pressure and low blood flow.
Blood vessels supplying the brain with nutrients and oxygen. vessels of the brain in patients with Alzheimer's disease hard and dense, they impede blood flow, allowing to accumulate amyloid.
Alzheimer's disease is one of the most serious public health problems. Nation Laboratory at the University focuses on the cognitive changes associated with age-related changes in vascular structure and function.
To measure the resistance of the vessels of the brain, scientists have calculated the index - the ratio of the average blood pressure in cerebral blood flow. A high index indicates that amyloid levels increase, and the risk of dementia.
The database used for the study includes data from 1,000 volunteers 55-90 years. These include cognitive test results, brain scans and information on blood biomarkers.
Nation used data from three groups of male and female volunteers: those who did not have amyloid accumulation in the brain, those who have savings, and those who had Alzheimer's disease. People with Alzheimer's disease lower blood flow in the brain. These changes in blood flow were not detected in the early stages of the disease when amyloid is accumulated, and there were no obvious signs of memory loss. People with Alzheimer's also significantly exceeded the rate of cerebrovascular resistance.
Cognitive function of amyloid patients deteriorated. Just two years after the initial survey they had more risk of cognitive decline and progression of clinical dementia.
"The results show that the change in resistance may be an early and major phenomenon in the brain, which is closely related to the symptoms of cognitive decline in the future", - says Nation.
Among the most promising drugs for Alzheimer's - statins, cholesterol-lowering, and drugs that reduce blood pressure, known as angiotensin receptor blockers. Nation found that people taking medications that reduce blood pressure, better memory.
Measuring index using brain scanners Nation is going to keep track of how drugs that reduce blood pressure, affect the resistance of the blood vessels in the brain of people at risk of Alzheimer's disease.