What causes stroke?

Stroke can happen to anyone, of any age and at any time.

There are different types of stroke, but ultimately, a stroke is a blood clot or bleed in the brain and can lead to permanent neurological damage, complications and sometimes death.

There are different types of strokes, depending on whether the disruption in blood flow resulted from a blockage or a burst:

• Ischaemic stroke: the blood vessels in the brain are blocked by a clot or have become too narrow for blood to get through. The reduction in blood flow causes brain cells in the area to die from lack of oxygen. This is what happens in 80% of all strokes.
• Haemorrhagic stroke: the blood vessel bursts, rather than being blocked. This results in blood leaking into the brain and causing damage.
• Subarachnoid haemorrhage: there is bleeding into the area around the brain known as the subarachnoid space. This is usually due to a burst aneurysm, which is a weakness in the blood vessel wall.

Sometimes, a person will have a transient ischaemic attack (TIA) or a ‘mini-stroke’. This is caused by a temporary disruption in the blood supply to part of the brain. The individual usually makes a quick recovery, but a TIA must be taken seriously as it can increase the likelihood of a stroke in the future. Be sure to check out our TIA awareness page and animation.

There are, however, a number of warning signs that will increase the likelihood of an individual being affected by stroke. High blood pressure is the most important and others include a previous stroke or transient ischemic attack (TIA), diabetes, high cholesterol, cigarette smoking and atrial fibrillation.

Doctors refer to these conditions as ‘modifiable’ risk factors, as they can usually be controlled, treated or changed. Visit our "How to prevent a Stroke" section for more information on how simple lifestyle changes can reduce the likelihood of you or your loved one experiencing stroke.