Stroke Risk: Normal Blood Pressure, Any Danger?

High blood pressure, or hypertension, is a major risk factor for strokes. It is the biggest single risk factor, playing a part in about half of all strokes. However, some individuals with normal blood pressure can still experience a stroke. In a 2005 study, 12% of people with normal blood pressure experienced a stroke. While high blood pressure is a serious condition that can lead to strokes, there are things you can do to reduce your risk of having one.

High blood pressure is the biggest single risk factor for stroke

High blood pressure, or hypertension, is the biggest single risk factor for strokes, playing a part in about half of all strokes. It is a serious condition, but there are ways to reduce the risk of a stroke.

High blood pressure is when the force inside your arteries is consistently too high. This can happen for a number of reasons, including lifestyle factors and health conditions. For example, eating too much salt, sleep apnoea, lupus, and the use of illegal drugs such as cocaine can all cause high blood pressure.

Over time, high blood pressure can damage and weaken the blood vessels, making it easier for blood clots to form or for arteries to rupture. This can lead to two types of strokes:

• Ischaemic stroke: High blood pressure causes a build-up of fatty material, known as atherosclerosis, which narrows the blood vessels. This can cause clots to form, and if a clot travels to the brain, it causes an ischaemic stroke.
• Haemorrhagic stroke: High blood pressure can damage and weaken blood vessels inside the brain, causing them to burst and bleed. This is known as a haemorrhagic stroke.

High blood pressure can also lead to small vessel disease, which increases the risk of a stroke and can affect cognitive function.

To reduce the risk of a stroke, it is important to manage high blood pressure through treatment, medication, and lifestyle changes. Maintaining a healthy blood pressure range is one of the best ways to lower the risk of a stroke. A healthy blood pressure is considered to be a systolic pressure of less than 120 mm Hg and a diastolic pressure of less than 80 mm Hg. Doctors recommend keeping blood pressure below 130/80 mm Hg to prevent a first-time stroke.

Lifestyle changes that can help lower blood pressure include:

• Eating a heart-healthy diet, such as the Mediterranean diet or the DASH diet
• Exercising regularly (at least 150 minutes a week of moderate-intensity aerobic activity)
• Losing weight if overweight or obese
• Reducing salt intake
• Quitting smoking
• Limiting alcohol consumption
• Getting 7-9 hours of sleep regularly
• Managing stress in healthy ways

Chronically low blood pressure also raises the risk of stroke

While high blood pressure is a well-known and major risk factor for strokes, chronically low blood pressure can also increase the risk of experiencing a stroke. Research has shown a link between low blood pressure and an elevated risk of dying from a stroke. However, scientists are still unsure why low blood pressure raises the risk.

In a 2021 study, people with a systolic blood pressure of less than 120 mm Hg, a diastolic blood pressure of less than 60 mm Hg, and a pulse pressure of at least 90 mm Hg were at a higher risk of dying from a stroke compared to those with typical blood and pulse pressure. Additionally, people with systolic blood pressure below 120 mm Hg and at least one other health risk factor were at the highest risk of dying from a stroke. These risk factors included high alcohol consumption, heart problems, and nutritional deficiencies.

Orthostatic hypotension, a sudden drop in blood pressure when standing up from sitting or lying down, has been linked to an increased risk of ischemic stroke. A 2018 study found that people with orthostatic hypotension had double the risk of having an ischemic stroke compared to those without the condition. A sharp drop in blood pressure can also cause a transient ischemic attack (TIA) or ministroke, due to the temporary reduction in blood flow to the brain.

Low blood pressure may also increase the risk of in-hospital complications after a stroke, such as gastrointestinal bleeding and sepsis. A 2021 study suggested that people with low blood pressure immediately after stroke treatment are more likely to have poorer outcomes, even after accounting for other cardiovascular conditions and stroke severity.

High blood pressure can lead to blood clots in the brain

High blood pressure, or hypertension, is the leading cause of strokes. It is a major risk factor and plays a part in about half of all strokes. While it is a serious condition, there are ways to reduce your risk of a stroke.

Secondly, high blood pressure can also cause blood clots by weakening the blood vessels and making them more prone to rupture. When a weakened blood vessel ruptures in the brain, it is known as a haemorrhagic stroke.

High blood pressure can also increase the risk of stroke by causing small vessel disease. This involves damage to the tiny blood vessels deep inside the brain, which makes a stroke more likely and can affect cognitive abilities such as thinking and reasoning.

To reduce the risk of stroke, it is important to manage high blood pressure. This can be done through lifestyle changes such as a healthy diet, regular exercise, weight loss, reducing salt and alcohol intake, and managing stress. Medication may also be prescribed if lifestyle changes are not enough to lower blood pressure.

High blood pressure can cause bleeding in or around the brain

High blood pressure, also known as hypertension, is a major risk factor for strokes. It is the biggest single risk factor and plays a part in about half of all strokes. Over time, high blood pressure can weaken and damage the walls of your blood vessels, making it easier for blood clots to form or for arteries to rupture. This can lead to two types of strokes: ischaemic strokes and haemorrhagic strokes.

Haemorrhagic strokes, or brain bleeds, occur when a weakened blood vessel in the brain starts to leak or suddenly bursts. This can happen inside the brain tissue or outside it. When they happen outside the brain tissue, they involve one or more of the protective layers (membranes) that cover the brain. There are three types of haemorrhagic strokes that occur outside the brain tissue:

• Epidural bleed: This occurs when blood collects between the skull bone and the outermost membrane layer, called the dura mater.
• Subdural bleed: This occurs when blood leaks between the dura mater and the thin layer beneath it, called the arachnoid mater.
• Subarachnoid bleed: This occurs when blood collects below the arachnoid mater and above the delicate inner layer beneath it, the pia mater.

Intracerebral haemorrhage is a type of haemorrhagic stroke that occurs inside the brain tissue. It is the second most common cause of stroke and is usually due to long-term, untreated high blood pressure. Intraventricular haemorrhage is another type of haemorrhagic stroke that occurs within the ventricles of the brain.

High blood pressure can also lead to ischaemic strokes, which account for about 87% of all strokes. Ischaemic strokes occur when an artery that supplies blood to the brain becomes blocked by a clot. This can happen in two ways: thrombotic strokes and embolic strokes. In a thrombotic stroke, the clot forms in a diseased artery within the brain itself. In an embolic stroke, the clot forms outside the brain and then travels to the brain, lodging in a previously normal artery.

Lifestyle changes can help reduce the risk of stroke

Yes, it is possible to have a stroke with normal blood pressure. While high blood pressure is a major risk factor for strokes, studies have shown a link between low blood pressure and an increased risk of stroke.

Regardless of your blood pressure, making lifestyle changes can help reduce your risk of having a stroke. Here are some ways you can reduce your risk:

Exercise regularly:

Regular exercise keeps your blood flowing and your heart strong. Aim for at least 30 minutes of moderate-intensity aerobic activity, such as cycling or walking, every day. Even 10 minutes of exercise can offer health benefits.

Maintain a healthy diet:

A healthy diet, such as the Mediterranean diet, can help lower your risk of stroke. Eat plenty of fruits, vegetables, whole grains, and lean proteins. Reduce your salt and cholesterol intake, and limit your alcohol consumption.

Quit smoking:

All forms of tobacco can cause blockages in the arteries leading to the brain, increasing your risk of stroke. Quitting smoking will immediately lower your risk.

Manage your weight:

Obesity contributes to high blood pressure, cholesterol, diabetes, and heart disease, all of which are risk factors for stroke. Losing weight can significantly reduce your risk of having a stroke.

Treat underlying conditions:

If you have underlying conditions such as atrial fibrillation, high blood pressure, high cholesterol, or diabetes, work with your doctor to manage these conditions. Taking medication or making lifestyle changes can help reduce your risk of stroke.

Manage stress:

Constant psychological pressure and stress can damage artery walls, increasing your risk of stroke. Find healthy ways to manage and reduce your stress levels, such as through positive self-talk and healthy lifestyle choices.

Frequently asked questions