The Link Between High Blood Pressure and Stroke

Nearly half of American adults have high blood pressure, according to the Centers for Disease Control and Prevention (CDC). Also called hypertension, the American Stroke Association (ASA) considers high blood pressure to be the top controllable risk factor for stroke.

A stroke occurs when something stops the flow of blood to brain cells, or a blood vessel breaks and leaks blood into the brain. As a result, brain cells die. The ASA cites strokes as the fifth leading cause of death, and a top cause of disability, in the United States.

Christopher David Anderson, MD, MSc, chief of the stroke division at Mass General Brigham, explains how high blood pressure increases stroke risk, and how you can protect your health.

How does high blood pressure cause stroke?

Hypertension affects your arteries, the blood vessels that carry oxygen- and nutrient-rich blood from your heart to the rest of your body. When blood pressure is high, blood flows through arteries with more force than it should. This excess force puts pressure on your arteries, damaging them.

“High blood pressure can cause vascular injury, or what some people call hardening of the arteries,” says Dr. Anderson. “Plus, your blood vessels naturally become stiffer as you age, which causes blood pressure to rise.”

Hardening of the arteries is also known as arteriosclerosis. Different types of vascular injury can cause a stroke:

• Atherosclerosis occurs when plaque collects inside larger arteries, reducing blood flow. Plaque is made of fatty substances, cholesterol, and waste products. A piece of plaque can break off and travel through blood vessels. If the plaque gets stuck, it can stop blood flow in the brain and cause a stroke.
• Arteriolosclerosis affects the smaller arteries (arterioles) that branch from larger arteries. High blood pressure can stiffen arterioles in your brain, causing blockages that stop blood flow. It can also weaken the tiny arteries in the brain, making them more prone to tears and rupture.

Hypertension and stroke types

High blood pressure can cause different types of strokes:

• Ischemic strokes occur when a blood clot or piece of plaque blocks blood flow in an artery that supplies blood to the brain. Ischemic strokes are the most common, accounting for almost 9 in 10 strokes, according to the ASA.
• Hemorrhagic strokes occur when a blood vessel in the brain weakens and tears from the constant force of high blood pressure or other aging processes. Bleeding may occur inside the brain, or between the brain and skull. “Hemorrhagic strokes can be more damaging and difficult to treat,” says Dr. Anderson.
• Transient ischemic attacks (TIAs) are often called ministrokes. A blood clot, piece of plaque, or small artery tear stops blood flow to the brain for a few minutes, and then resolves on its own. TIAs are a sign that you’re at risk for having a stroke.

Tips to manage hypertension and lower stroke risk

Having high blood pressure doesn’t mean a stroke is in your future. In fact, the CDC estimates that up to 8 in 10 of strokes are preventable.

“Blood pressure medications and lifestyle changes can make a significant difference,” confirms Dr. Anderson.

These actions can help you achieve your target blood pressure and prevent strokes:

Take blood pressure medications

Blood pressure medications help keep blood pressure in a healthy range (below 120/80 millimeters of mercury or mm Hg). But finding the right medication, or combination of blood pressure medications, can be tricky.

“Everyone responds to these medications differently,” says Dr. Anderson. “What works for your spouse, sibling, or friend might not work as well for you. Or they might cause side effects.”

Fortunately, providers have a lot of blood pressure medications to choose from. Some work by relaxing blood vessels and stopping them from getting too narrow. Others work by widening blood vessels, so blood moves more freely with less pressure on arteries. There are also medications to ease stress on your heart by slowing the heartbeat. Finally, some medications help your kidneys get rid of excess water and salt, reducing how much fluid your heart must pump.

Your stroke risk is higher if you have high blood pressure along with diabetes and/or high cholesterol. Medications can also help control these conditions, like cholesterol-lowering statins.

Make lifestyle changes

In addition to taking blood pressure medications, you can also take steps to lower your blood pressure naturally:

• Eat a healthy diet: Fresh fruits and vegetables, whole grains, and healthy fats, such as those found in fish and avocados, are among the best foods to prevent stroke. You should also watch how much salt, sugar, and alcohol you have each day.
• Move more: Get at least 150 minutes of moderate-intensity aerobic exercise, or 75 minutes of vigorous exercise, every week. Regular exercise is good for your arteries. The increased blood flow during exercise helps arteries stay wider, flexible, and less prone to plaque.
• Lift weights: In addition to aerobic exercise, the American Heart Association recommends 2 days of moderate- to high-intensity strength-training exercises per week. Lifting weights or doing body resistance exercises keeps blood vessels healthy and working as they should.
• Maintain a healthy weight: Excess weight and obesity can cause high blood pressure because your heart has to work harder to pump blood. The extra weight also puts pressure on your kidneys, increasing blood pressure. A healthy diet and exercise can help. Some people benefit from weight loss medications or surgery.
• Seek help to quit tobacco: Using tobacco products raises blood pressure by narrowing arteries and making blood stickier and more likely to clot. Just breathing in secondhand smoke increases stroke risk by up to 30%, according to the CDC. These tips can help you quit smoking. Your primary care provider (PCP) can also help set you up for success.

Monitor blood pressure at home

Your blood pressure can change from moment to moment and day to day. Measuring your blood pressure at home can help gauge how well medications work. It can also help quickly detect a rise in blood pressure that needs immediate medical attention.

To get an accurate blood pressure reading:

• Sit for at least 5 minutes with your feet on the floor before taking a reading.
• Relax your arm at heart level on a table.
• Take your blood pressure in the morning and evening, at least 3 days a week.
• Average each day’s results and the weekly result.
• Keep a record of your blood pressure readings to share with your provider.
• Bring your home device to your provider’s office at least once a year to make sure it’s giving accurate results.

When to call your provider

You should call your provider any time you have concerns about your blood pressure or something feels off. It’s especially important to reach out if your blood pressure readings are above 130/80 mg HH for a week or more.

“You may need to change or add medications to get those numbers lower,” says Dr. Anderson. Your provider may also recommend participating in a remote blood pressure monitoring program.

Call 9-1-1 if you or someone you love shows signs of stroke, such as facial drooping, arm weakness, and speech difficulties.