What causes blood clots in young people? Experts weigh in after Hailey Bieber suffers ‘stroke-like’ symptoms

This week, model Hailey Bieber revealed she had been taken to hospital after displaying “stroke-like symptoms” as a result of a “very small” blood clot in her brain.

The 25-year-old said the clot had caused a lack of oxygen “but [her] body had passed it on its own and [she] recovered completely within a few hours”.

The NHS says blood clots are rare in young and healthy people, though some factors can increase risk. These include smoking, being on the combined contraceptive pill or having an inflammatory condition such as Crohn’s disease.

A blockage in an artery leading to the brain is the cause of the most common type of stroke, called ischemic strokes.

According to Stroke Association, around 85 per cent of strokes in the UK are ischaemic. Approximately 15 per cent are caused by bleeding in and around the brain, a condition known as haemorrhagic stroke.

The injury to the brain caused by a stroke can lead to widespread and long-lasting problems. While some people may recover quickly, others need long term support.

We asked experts how common blood clots like Bieber’s are in young people, and how they are caused.

Bieber’s symptoms are similar to those seen in a “mini stroke” or a transient ischaemic attack (TIA), Professor Pankaj Sharma, a consultant neurologist at Imperial College London says.

These usually last less than 24 hours, and in most cases, less than one hour. As the clot is small, most people who suffer from mini strokes make a full recovery.

This is because the clot is small enough to still be moved along the circulatory system, dissolving as it moves. “If it’s small it will obviously move quickly and dissolve quickly to complete disappearance,” Sharma explains.

There are a number of causes of blood clots in young people, Nick Ward, a professor of Clinical Neurology and Neurorehabilitation at University College London, explains.

“Blood likes to keep moving around,” so they may form when a person has poor circulation.

Some conditions, such as Hughes syndrome, cause the blood to become “sticky”, increasing the risk of clotting.

Hughes syndrome is when a person’s immune system produces abnormal blood proteins which cause blood platelets to clump together.

Blood clots may also form because of damage to blood vessels.

An example of this is carotid dissection, which is when two of the arteries located in the front of the neck on either side tear from trauma. This may occur from even a mild injury, Sharma says. “This can allow clot to form and head towards the brain.”

“Clots then get stuck in arteries in the head, starving the tissue of oxygen,” Ward adds.

“The tissue will be dead in about 10 mins. If the artery spontaneously unblocks before then – symptoms will last about 10-20 mins – but there is no tissue damage, it’s a TIA.”

In young people, a small hole in the heart, named a patent foreman ovale (PFO) may also cause a blood clot.

The hole allows a passage of blood to directly leak from the right side of the heart, where blood is un-oxygenated, to the left side of the heart, where it is oxygenated.

“This abnormal anatomy allows the opportunity for a small clot to pass through from the right to the left and then directly to the brain,” Sharma explains.

Sharma says strokes in young people are often due to PFO.

“That is because if it is to cause a problem it usually does so by then. As we age other risk factors begin to play a greater risk factor for stroke, such as high blood pressure, obesity, and cholesterol.”

Blood clots and TIAs are not common in young people.

In England, one in six people will have a stroke in their lifetime, according to Public Health England. The median age of strokes in men is 70, while in women it is 76.

Of the 100,000 people who suffer from a stroke in the UK every year, approximately 50 are first-time TIAs.

The Stroke Association says having a TIA is a warning sign that you are at risk of having a stroke.

“The risk is greatest in the first days and weeks after a TIA. So you urgently need to find out what caused it, and get advice and treatment to help you stay healthy,” it added.