Understanding How High Blood Pressure Causes Stroke

The Centers for Disease Control and Prevention (CDC) estimate that about half of all American adults¹ have high blood pressure. High blood pressure (BP) is a primary cause of stroke. Stroke is among the top causes of death worldwide and one of the leading causes of disability.

In medical terms, high BP is known as hypertension. According to the World Health Organization (WHO), high blood pressure is a “condition in which the blood vessels have persistently raised pressure[...]the higher the pressure, the harder the heart has to pump.”

When you have high blood pressure, it not only makes your heart work harder; it can damage the blood vessels supplying your brain.

In this article, you'll learn how your high blood pressure can go before a stroke becomes a likely risk, as well as ways to lower your blood pressure preventatively.

First, what is a stroke?

A stroke is a medical emergency that happens when blood flow to your brain is blocked or stopped or one of the arteries supplying blood to the brain bursts (from high pressure).

Your brain requires a constant supply of nutrients and oxygen to function. So, if that supply is interrupted (even quickly), serious problems arise.

After a few minutes without oxygen or blood, your brain cells start dying, which may prevent you from performing activities controlled by the affected area(s) of the brain, such as walking or speaking.

Atherosclerosis is a condition that involves hardening and thickening of the artery walls, and it can also narrow and clog your arteries with fatty plaques, causing clots to form in the blood vessels supplying the brain. Hypertension accelerates this process.

Functions that get disrupted by a stroke may include one or more of the following:

• Movement

• Eating

• Speech

• Memory

• Thinking clearly

• Controlling bodily functions

• Emotional regulation

Symptoms of a stroke

The following are common symptoms of a stroke:

1. Sudden confusion/difficulty understanding what others are saying 

2. Slurred speech

3. Facial drooping/numbness on one side

4. Weakness of the arms or legs 

5. Blurred vision, double vision, or loss of vision 

6. Severe and sudden headache

7. Dizziness

If you suspect that you or someone you know is having a stroke, call 911 immediately.

Understanding stroke risk factors

The risk of a stroke is never zero at any age, but the sooner you start controlling and managing your blood pressure, and any other risk factors, the better.

In recent years, much information about preventing strokes has been shared with healthcare professionals and the public. Many Americans have adapted their lifestyle through changes to their eating habits and quitting smoking. This has led to a 70% reduction in death due to stroke over the last 50 years².

Stroke risk factors

You can reduce some of your risk factors through lifestyle changes or medical treatment.

A healthcare provider help manage certain controllable factors for stroke, such as:

• Blood pressure level

• Alternatives to oral contraceptives  

• Smoking cessation

• Diabetes management

• Obesity

• Drug use

• Alcohol consumption

• High cholesterol

Fixed, or non-manageable risk factors include:

Age The incidence of stroke has been reported to double with each decade after the age of 55 years, and over 70% of all strokes occur after the age of 65³.

Sex Men have a higher risk⁴ of developing both ischemic and hemorrhagic stroke than women.

Race Stroke has a higher prevalence among Black Americans which may be attributed to a higher incidence of hypertension⁵.

Family history Stroke risk factors can be high in some families because of a genetic predisposition to stroke, or a higher genetic tendency for diabetes or high blood pressure. 

How high can your BP go before increasing the risk of a stroke?

One of the best ways to limit the chance of a stroke is to measure and monitor your blood pressure regularly. If you have a blood monitor at home and have high blood pressure, it's a good idea to take your pressure readings twice daily.

Health professionals measure blood pressure using systolic and diastolic blood pressure numbers.

Systolic blood pressure is the pressure within your arteries as your heart beats. Normal systolic blood pressure is below or equal to 120 mm Hg.

Diastolic blood pressure measures blood pressure when your heart rests on refilling with blood. 

Normal diastolic pressure is lower than or equal to 80 mm Hg.

If you have consistent blood pressure levels over 130/80 mm Hg⁶, that is consistent with hypertension.

Ongoing blood pressure levels of 120/80 mmHg–140/90 mmHg are a warning sign that you could develop chronic hypertension and increase your risk of stroke.

A single blood pressure reading is insufficient to diagnose high blood pressure.

You may get anxious in a medical environment, raising your blood pressure. So, your doctor may give you a 24-hour monitor to assist you with tracking your blood pressure.

If you are pregnant, using oral contraception, under hormone replacement therapy (HRT), or taking blood pressure medication, get your blood pressure checked regularly.

What is a hypertensive crisis?

If a sudden and quick elevation in the blood pressure occurs (often above 180/120) it can damage your blood vessels. In a hypertensive crisis, your heart is unable to pump blood effectively. The following are common causes of a hypertensive crisis:

• Not taking prescribed blood pressure medication

• Heart attack

• Kidney failure

• Heart failure 

• Complications during pregnancy 

• Ruptured main artery (aorta)

• Drug interactions

It is vital to call 911 immediately if your blood pressure is severely high or if you have hypertension and experience any of the below symptoms.

Some of the symptoms of a  hypertensive crisis that are important to note:

• Severe headache

• Blurred vision

• Severe chest pain

• Shortness of breath

• Nausea and vomiting

• Confusion

• Severe anxiety

• Unresponsiveness

• Seizures

How does hypertension cause a stroke?

High blood pressure strains your arteries constantly, weakening them. These arteries can easily clog and burst, increasing the risk of a stroke. Hypertension causes blood vessels to narrow and increases the chances of blood clots. Therefore, managing your blood pressure is a crucial way to decrease your chances of having a stroke.

There are two primary types of stroke, ischemic and hemorrhagic stroke. The former is more common and accounts for over 87% of strokes⁷.

Hypertension can also cause temporary mini-strokes referred to as transient ischemic attack (TIA). In this case, clots get dissolved or dislodged naturally. Most individuals suffering from TIA fully recover from the condition, but it's a warning sign that you can incur a full-blown stroke in the future. 

High blood pressure and preventing a stroke

Even though hypertension is a risk factor for stroke, over 11 million Americans⁸ are unaware that they have high blood pressure. So, the best solution for fighting high blood pressure and stroke is regular checkups by a qualified healthcare provider.

Some of the ways to reduce hypertension and the chance of a stroke include:

Make the best possible dietary choices Eat more fruits, fiber, and green vegetables. Also, limit your intake of salt, saturated fats, coffee, and sugar.

Maintaining a healthy weight Obesity is a risk factor for hypertension, diabetes, and stroke.

Stop smoking If you smoke cigarettes, quitting will lower your chances of having a stroke.

Limit or stop drinking alcohol Excessive alcohol intake⁹ can raise your blood pressure.

Regular exercise Get at least 30 minutes of aerobic activity a day.

Minimize stress Chronic stress increases the likelihood of a stroke.

Follow medication recommendations Strictly follow your healthcare provider's instructions about taking your medicines. Some of the medications¹⁰ that can help to prevent stroke include:

• Antiplatelets These are medications such as aspirin which doctors prescribe to stroke patients. They help lower the chance of the formation of blood clots.

• Blood-thinners Your doctor may prescribe blood thinners if you have the high blood pressure to help prevent the formation of clots in your body.

• Blood pressure medication Take blood pressure medication according to a doctor's prescription to help limit the chances of developing a stroke.

• Heart medication If you have a heart problem, your doctor may prescribe medication to limit the chances of developing a stroke.

• Cholesterol-lowering medication Buildup of cholesterol on your blood vessels can increase the chances of stroke. Cholesterol-lowering drugs can help to reduce the chance of stroke.

• Diabetes medication Insulin adjusts your blood sugar levels and can limit the risk of a stroke.

When to seek medical attention

Seek urgent medical attention/call 911 immediately if your blood pressure measures 180/120 or higher. If you are diagnosed with hypertension, or you have one or more of the risk factors mentioned earlier, set aside time to develop a risk management strategy with a doctor.

The lowdown

High blood pressure is a leading cause of stroke. Understanding your BP readings and carefully managing any risk factors can help limit the chances of having a stroke.  If you suffer from high blood pressure, take your medicines as per your doctor's recommendation. Also, seek immediate help anytime you notice a drastic increase in your blood pressure.