Common sleep condition which affects 10 million Britons could increase the risk of deadly brain bleeds

Millions of adults with a common sleep disorder could be at greater risk of suffering a potentially deadly brain bleed, concerning new research suggested today. 

Obstructive sleep apnoea occurs when the walls of the throat relax and narrow during sleep, causing a temporary lapse in breathing. 

During an episode, the lack of oxygen triggers the brain to pull a sleeper out of deep sleep so that their airways reopen. Previous research has shown that sleep apnoea sufferers are more likely to develop heart disease, kidney disease and lung cancer. 

Now Korean researchers say it could increase the risk of suffering a brain bleed—known as cerebral microbleeds (CMBs)—which are associated with an increased risk of debilitating stroke and dementia. 

The researchers say their findings ‘add to the evidence for the importance of sleep apnoea to brain health’ and hope that it will now be considered a target for early diagnosis and treatment to help prevent brain bleeds, stroke and dementia in ageing populations. 

In the study, published in Jama Neurology, researchers analysed data from 1,441 patients aged around 60 from the Korean Genome and Epidemiology Study, using an at home sleep test. 

Considered the gold standard of sleep tests, patients were hooked up to a polysomnogram machine by a trained technologist before they went to sleep, who then returned the morning after to collect the results. 

Sleep apnoea was defined as a reduction in airflow by 90 per cent for at least 10 seconds, with ongoing respiratory efforts. 

Patients then underwent brain scans to identify and signs of a brain bleed. 

Participants also completed a questionnaire about exercise levels, smoking and drinking status, and were asked by a trained examiner about their medical history and lifestyle. 

Body-mass index (BMI), blood pressure, blood glucose and cholesterol levels were all tested at the start of the study, after four years and again a further four years later.  

At the beginning of the study, just over 30 per cent of participants had mild OSA, whilst around 13 per cent had moderate to severe OSA. 

None of the participants had a history of heart disease.  

The researchers noted that BMI—a measure of body fat based on height and weight—was significantly higher in the moderate to severe group, averaging 26.11, which is considered overweight.

However, both groups reported a similar level of exercise, though those who suffered more severe OSA were more likely to smoke and drink. 

The researchers found that moderate to severe OSA sufferers were more than twice as likely to suffer a brain bleed than those with moderate OSA after fours years. 

After eight years, over 7 per cent of participants with moderate to severe OSA had suffered a brain bleed, compared to just 3 per cent of those with a less severe form of the disorder.   

Whilst the exact mechanism behind the link between sleep apnoea and brain bleeds is not fully understood, the researchers suggested it could be a result of high blood pressure, exacerbated by repeated episodes of low blood oxygen. 

Sleep apnoea has been previously associated with blood pressure surges, which could be particularly damaging, however the researchers found that the risk remained even after accounting for high blood pressure.

Another potential explanation could be the rise in oxidative stress, which leads to the production of free radicals which can damage cells in the brain, increasing the risk of a bleed. 

OSA has also been linked with inflammatory responses which make vessels more susceptible to bleeding.

The researchers  acknowledged that their study had some limitations, given that almost all of the brain bleeds recorded were single microbleeds. 

This meant that they were unable to make any observations linking the severity of the sleep disorder with the severity of the bleed. They also noted that there could be a potential healthy cohort effect due to the long term follow up. 

Currently, there is no drug licensed for the condition, and patients are often prescribed continuous positive airway pressure (CPAP)—a machine that delivers air through a mask at night. 

 

But as many as half of those with the disorder struggle to stick to using the machine. 

Studies have also shown that cutting back on alcohol, quitting smoking and eating a healthy balanced diet that avoids ultra-processed , sugary and high-fat dairy products can help. 

Being overweight or obese can also drive the risk of OSA—with figures showing that half of people with a BMI over 40 will suffer the condition. 

The findings come as millions with undiagnosed sleep apnoea could soon benefit from a revolutionary gadget, called AcuPebble SA100, a small device that sticks to a patient’s neck. 

A 2022 study published in the BMJ found that the device was nearly as effective as gold-standard sleep studies, with experts saying its real benefit is the scale at which it can be delivered.

The company says it could be used to identify patients who may not have realised they have sleep apnoea but are at high risk.