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Home Stroke What causes a Stroke

What causes a Stroke

Older people are particularly at risk of having a stroke which happens when the blood supply to part of the brain is disrupted or cut off. Affecting 100,000 people every year, the good news is that understanding the causes of a stroke, recognizing the warning signs, and taking action can significantly reduce the risk of having a stroke. This guide provides practical information about what causes a stroke, why they happen and important risk factors. 

Why do strokes happen?

A stroke occurs when the blood supply to the brain is cut off, either by a blood clot or a ruptured blood vessel in the brain.

There are three main types of stroke, all of which occur due to the same range of causes: the most common type, responsible for 80% of strokes, is an ischaemic stroke, when a blood clot forms to block the flow of blood and oxygen to the brain.  This may happen because the arteries have become narrower, or blocked, a process called atherosclerosis, something which occurs with age. 

Why do strokes happen

Less common, a haemorrhagic stroke, happens when a blood vessel inside the skull bursts and bleeds into and around the brain.  They can also be caused by the expansion of a blood vessel, known as a brain aneurysm.

A Transient Ischaemic Attack (TIA) – known also as a mini-stroke – is the same as both types of stroke, but TIAs tend to only last a short time – minutes/hours – before the symptoms disappear.   

Main causes of stroke and risk factors

There are a number of causes and risk factors associated with strokes:

High Blood Pressure

High blood pressure, also called hypertension, plays a part in half of all strokes.  For some the symptoms of high blood pressure – dizziness, nose bleeds, headaches, blurred vision – only start when it has been high for some time, so having high blood pressure can be hard to know without regular monitoring and health checks. 

Lifestyle changes such as reducing salt in the diet, healthy eating and taking regular exercise can have a marked impact on reducing high blood pressure and the risk of a stroke.  In some cases medication – ACE inhibitors – may be necessary.  


Atrial Fibrillation

Atrial fibrillation (AF) is a heart condition that causes an irregular or abnormally fast heartbeat. It means that the heart doesn’t always empty itself of blood at each beat. A clot can form in the heart and travel to the brain, causing a stroke.

Symptoms of AF can include heart palpitations, dizziness, shortness of breath, chest pains or fatigue. Medical assistance should be sought in any event for someone with these symptoms, but also to determine the cause.  Tests will be carried out to determine the nature of the AF, and the best treatment plans.

Depending on the diagnosis, as well as medical history and general health, medication may be prescribed including anti-arrythmyics  to control the heart rate; beta blockers to help restore a normal heart rhythm; anticoagulants, or warfarin may also be prescribed to prevent blood clots. 


Diabetes causes high levels of sugar in the blood. Over time this damages the blood vessels, which can lead to clots forming.Type 2 diabetes is the most common, and it is more likely to happen if you are overweight. 

Diabetes is a cause of strokes

Medication might be needed to manage the Diabetes, or to reduce the likelihood of a blood clot. For many, healthy eating, losing weight and being active can have a significant impact on the diabetes.

High Cholesterol

Cholesterol is a vital substance produced by the liver and found as a waxy substance in the blood.  Cholesterol is also found in meat and food from animals including dairy.  It helps build healthy cells, but if there is too much cholesterol in the blood it can damage the blood vessels, clogging up the arteries with fatty deposits, creating blockages with the blood supply being cut off, leading to heart a stroke.

You can reduce the amount of cholesterol eaten by reducing the amount of fatty foods and unsaturated fats you consume.  Statin medication is likely to be prescribed to reduce the amount of cholesterol in the blood stream, which in turn will help reduce the risk of a TIA or stroke.

General lifestyle

There are a number of contributory risk factors to the chances of having a stroke that can be managed through a change in lifestyle: Anxiety and stress themselves, but also when combined with high blood pressure, or for example, being overweight.

Smoking: Tobacco use raises blood pressure, narrows arteries, and promotes the formation of blood clots.

Sedentary lifestyle: Lack of physical activity contributes to obesity, hypertension, and other risk factors associated with strokes.

Poor diet: High intake of saturated fats, cholesterol, and sodium increases the risk of developing high blood pressure and other stroke-related conditions.

Minimizing stroke risk factors

The best advice for minimising the risk of a stroke includes:

  1. Regular check-ups with the GP or community nurse to monitor blood pressure, cholesterol levels, and overall health. Increasingly there are also monitoring services available, in the home, as wearables and also mobile apps which can also keep daily/hourly track of vitals.
  2. Take prescribed medications as directed by the GP or pharmacist, particularly for managing conditions like hypertension, diabetes, and atrial fibrillation.
  3. Eat a balanced diet rich in fruits, vegetables, whole grains, lean proteins, and low in saturated fats, cholesterol, and sodium. Have cholesterol levels checked regularly, and take action to reduce cholesterol as prescribed by the medical professionals;
  4. Eat well and healthily and take regular exercise: a walk every day, exercise classes can help to minimise the risk of a stroke;
  5. Stop smoking and drink less alcohol; these hardly need saying now, but are a high contributory risk to having a stroke;
  6. Manage stress: easier said than done sometimes, but there are exercises and techniques to help reduce stress such as medication and breathing;

Spotting Warning Signs of strokes

Recognizing the signs of a stroke is crucial for prompt medical attention. The acronym FAST can help identify stroke symptoms:

Face: If one side of their face droops or appears uneven, it may indicate a stroke.

Arms: try to raise both arms. If one arm drifts downward or is weak, it may be a sign of a stroke.

Speech: repeat a simple phrase. Slurred or garbled speech can indicate a stroke.

Time: Time is of the essence. If any of these signs are observed, dial 999 immediately for an ambulance

Looking after yourself to reduce risks of stroke

By understanding the main causes of stroke, recognizing warning signs, and taking steps to minimize the risk, elderly people can significantly reduce their chances of experiencing a stroke. Regular check-ups, medication as prescribed, a healthy lifestyle, and managing underlying health conditions all contribute to stroke prevention.

Regular exercise to reduce risk of strokes

You can find out more about treatments for and recovery from Strokes in our guide.  There are organisations including the Stroke Association who provide local support and resources to help.