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Causes - Transient ischaemic attack (TIA)

Transient ischaemic attacks (TIAs) happen when one of the blood vessels that supply your brain with blood becomes blocked.

This stops your brain from working as normal. This can lead to symptoms such as slurred speech and weakness.

In TIAs, the blockage is temporary. Your brain's blood supply returns to normal before there's any real damage.

The blockage is usually caused by a blood clot. It can also be caused by pieces of fatty material or air bubbles. In very rare cases, a TIA can be caused by a small amount of bleeding in the brain known as a haemorrhage.

Blood clots

Blood clots that cause TIAs may form in areas where arteries have been narrowed or blocked over time. Fatty deposits known as plaques cause the blockage or narrowing.

As you get older, your arteries can naturally become narrower.

Things that can speed up this process include:

A type of irregular heartbeat called atrial fibrillation can also cause a TIA. It can lead to blood clots escaping from the heart and becoming lodged in the blood vessels supplying the brain.

Risks for a TIA

Some things can increase your chances of having a TIA.

Some of the main risk factors are:

  • age – TIAs can happen at any age but they're more common in people over 55
  • ethnicity – people of south Asian, African or Caribbean descent have a higher TIA risk, partly because rates of diabetes and high blood pressure are higher in these groups
  • medical history – other health conditions such as diabetes can increase your risk of a TIA
  • weight – your risk of having a TIA is higher if you have obesity
  • diet – your risk is higher if you have a diet high in fat and salt
  • alcohol – drinking too much alcohol can increase your TIA risk
  • smoking - narrows your arteries and makes your blood more likely to clot

Changing some parts of your lifestyle can help to lower your risk of having a TIA or a full stroke.

Page last reviewed: 26 July 2023
Next review due: 26 July 2026