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High blood pressure and stroke risk

Untreated high blood pressure increases a person's risk of having a stroke.

Blood flow to an area in the brain is cut off in a stroke, which can cause brain damage and can be fatal.

The Stroke Association says high blood pressure is the single biggest risk factor for having a stroke and causes around half of all ischaemic strokes.

How does a stroke occur?

There are two types of stroke:

  • Ischaemic stroke is similar to a heart attack, except it occurs in the blood vessels of the brain. Clots can form either in the brain’s blood vessels, in blood vessels leading to the brain, or even blood vessels elsewhere in the body which then travel to the brain. These clots block blood flow to the brain’s cells. Ischaemic stroke can also occur when too much plaque (fatty deposits and cholesterol) clogs the brain’s blood vessels. Around 80% of all strokes are ischaemic stroke.
  • Haemorrhagic strokes occur when a blood vessel in the brain breaks or ruptures. The result is blood seeping into the brain tissue, causing damage to brain cells. The most common causes of haemorrhagic stroke are high blood pressure and brain aneurysms. An aneurysm is a weakness or thinness in the blood vessel wall that causes it to balloon outward.

Signs of stroke

If you experience any of the following signs you or a loved one may be having a stroke, call 999 immediately.

  • Sudden numbness or weakness in the face, arm or leg (especially on one side of the body)
  • Sudden blurred vision or decreased vision in one or both eyes
  • Sudden inability to move part of the body (paralysis)
  • Sudden dizziness or headache with nausea and vomiting
  • Difficulty speaking or understanding words or simple sentences
  • Difficulty swallowing
  • Dizziness, loss of balance or poor coordination
  • Brief loss of consciousness
  • Sudden confusion

The Fast - Face Arm Speech Time - test is used to help diagnose stroke prior to a person being admitted to hospital. Fast is an assessment of three specific symptoms of stroke:

Facial weakness - can the person smile? Has their mouth or eye drooped?
Arm weakness - can the person raise both arms?
Speech problems­ - can the person speak clearly and understand what you say?

Time to call 999 if the person has failed any one of these tests.


A transient ischaemic attack (TIA), often called a “mini-stroke”, may be a warning of an impending stroke. It typically consists of the same signs and symptoms of stroke, but the symptoms are temporary and full recovery occurs within 24 hours. It happens when blood flow to a certain part of the brain is cut off for a short period of time, usually 15 minutes or less. A TIA can occur anywhere from a few minutes to several months before a stroke. A TIA is a painless episode but it is a warning that something is wrong. It should be treated as seriously as a stroke.

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