We typically think of high blood pressure as a risk factor for heart attacks. But it can also cause serious harm to our brains. Left untreated, high blood pressure can lead to small “silent strokes,” cognitive impairment, and dementia.
Hypertension, the clinical term for high blood pressure, is a disease that results in an above average amount of pressure on the walls of our arteries. Over time, this pressure damages the blood vessels. Though it can cause a range of health problems, hypertension is particularly dangerous for the brain .
Arteries carry vital oxygen and glucose to our brains. And because the brain is a resource hog—it accounts for just 2 percent of our body weight but uses
20 percent of our available oxygen and calories —minor problems with blood vessels and blood flow can have major consequences.
Researchers note that:
“brain tissue deprived of oxygen and glucose as a result of compromised blood supply is likely to sustain transient or permanent damage."
Doctors can see the damage on MRI brain scans. The scans can reveal small strokes and “hyperintensities” deep in the brain’s white matter, which indicate cerebral small vessel disease. This damage in white matter can lead to vascular cognitive impairment and vascular dementia, which is the second most common form of dementia.
Hypertension is also recognized as a risk factor for Alzheimer’s disease.
But there is some good news. Some studies suggest proper treatment of hypertension can reduce dementia risk by as much as 50 percent . And several clinical trials are studying whether anti-hypertensive drugs might be beneficial for dementia prevention and treatment.
At Sunnybrook Research Institute in Toronto, Dr. Sandra Black is comparing two popular classes of anti-hypertensive drugs to see which better protects the brain from vascular damage. Using available data, she has already found that angiotensin receptor blockers reduced dementia risk significantly more than ACE-inhibitors. Dr. Ihab Hajjar at Emory University is conducting a clinical trial of candesartan , a type of angiotensin receptor blocker, to test its potential to prevent or slow the development of Alzheimer’s in patients with mild cognitive impairment.
Both of those studies focus on Alzheimer’s, but others are working on vascular dementia. At St George's, University of London, Dr. Atticus Hainsworth is testing tadalafil (commonly known as Cialis) in patients with cerebral small vessel disease to see if it can improve blood flow and treat vascular dementia.
All of the studies mentioned were supported by the Alzheimer’s Drug Discovery Foundation, where I am the Chief Science Officer. Other funders are joining our efforts.
Earlier this year, the NIH’s National Institute of Neurological Disorders and Stroke announced a consortium to study vascular contributions to cognitive impairment and dementia.
The group will focus on the development of better diagnostic tools for vascular changes in the brain. This will enable researchers to identify patients with early signs of cerebral small vessel disease and treat them so they never develop dementia.
Soon, we will have effective treatments for vascular dementia. Today, you can lower your odds of developing it by managing hypertension.
