Undercovering link between cardiovascular disease and sleep apnoea

With an increasing number of people losing their lives to heart disease each year, researchers from the Kolling Institute have launched a first of its kind study using MRI technology to broaden scientific understanding of the link between cardiovascular disease and sleep apnoea.

The new study follows latest figures showing cardiovascular disease is the leading cause of death worldwide, killing one Australian every 12 minutes.

This makes the research important and timely, especially given that obstructive sleep apnoea is also increasing and now affects around one billion people. Known as the silent killer, this chronic disease causes low oxygen levels, sleep disturbance and dangerous pressure inside the chest.

Meet the team searching for answers

Royal North Shore Hospital respiratory and sleep medicine specialist Professor Peter Cistulli will lead the study, collaborating with RNSH Head of Respiratory and Sleep Medicine Dr Ben Harris, and Kolling Institute researchers Professor Martin Ugander and Dr Rebecca Kozor, who are experts in cardiac imaging.

The team behind the new study
Meet the team: Nina Sarkissian, Prof Martin Ugander, Prof Peter Cistulli, Dr Ben Harris and Dr Rebecca Kozor

Professor Cistulli said obstructive sleep apnoea has been linked to the development of cardiovascular disease, including hypertension, heart attack, atrial fibrillation and stroke – but there have been no randomised controlled trials confirming a causal link between the two.

“We hope our project will provide definitive evidence of the relationship between sleep apnoea and cardiovascular disease, closing our existing gaps in knowledge and informing future treatment approaches,” he said.

Nina Sarkissian, Director of Research Development for the Sleep Research Group across the Charles Perkins Centre and Royal North Shore Hospital, plays a key role in developing such cross-disciplinary collaborative research programs.

She said “Our CardioSleep Program will be unique, uniting three major disciplines of cardiology, respiratory and sleep medicine, and radiology to develop a precision medicine approach. This will help define which patients are at greatest risk and require personalised treatment.”

“We would like to see this valuable research program drive a new approach, and one which will dramatically reduce the number of people who lose their lives prematurely with a combination of sleep apnoea and cardiovascular disease.”

Nina Sarkissian

The project has been made possible following funding from the Ramsay Research Grant Program.

Snoring treatment is found to sharpen memory and focus

Treating the common snoring condition obstructive sleep apnea (OSA) can improve memory, focus and thinking skills. A study by the Woolcock Institute of Medical Research found that patients treated with the ‘gold standard’ OSA therapy can improve not just their sleep, but also their brain function.

The study by the Woolcock Institute of Medical Research in Sydney people found OSA patients who are treated with the gold standard therapy, CPAP, improve not just their sleep but their brain function when awake.

Largest study of its kind

The research, published in the prestigious international journal, Sleep, is the largest of its kind to confirm the brain benefits of the treatment.

“We were able to show improvements to multiple aspects of cognitive function, including working memory, sustained attention and executive function, not to mention improved sleep, mood and quality of life.”

Dr Angela D’Rozario, Lead researcher

More than 775,000 Australians have OSA, a breathing disorder in which the airway repeatedly closes during sleep. Many sufferers wake dozens of times each night as their breathing gets very shallow or even stops. During the day they’re left feeling sleepy and unable to concentrate, and have a higher risk of depression, cardiovascular problems and vehicle accidents.

Symptoms can be reduced with CPAP, or continuous positive airways pressure, which works by holding the airways open while patients’ sleep. However, patients can be reluctant to use CPAP nightly, or stick with the treatment long term.

The Woolcock team enlisted 167 people with OSA to test the impact of CPAP on brain functioning.

“We know that the repeated pauses in breathing that occur during the night in OSA can disrupt sleep patterns and specifically alter different types of brain wave activity that are important for optimal cognitive functions,” Dr D’Rozario explains. “So we thought we’d see whether the main treatment available can reverse this problem.”

Tracking treatment

Volunteers underwent a series of neurocognitive tests at the start and end of the six-month trial, and sleep patterns and brain wave activity were also tracked in two overnight lab stays.

“Excitingly, we found that brain wave patterns during sleep were boosted and performance improved in all areas of cognitive function we tested,” the sleep neurophysiologist says.

“On top of that, self-reported mood, daytime sleepiness, and quality of life relating to sleep also improved after six months of CPAP.”

A driving test simulation

By the end of the trial, patients were getting more deep slow wave sleep and REM sleep, which are important for learning and memory, and more of their in-bed time was spent sleeping. There were also fewer breathing pauses and wake-ups in the night, Dr D’Rozario says.

Impacting brain health

“This shows CPAP can reverse brain wave activity abnormalities during sleep and restore healthy sleep patterns,” she says. “We’re thrilled to see CPAP clearly has a positive impact on brain health. Hopefully this encourages more Australians to use it.”

The team plan to test whether these short term benefits translate to a lower risk of mild cognitive impairment and dementia in the longer term.

The study also involved researchers from Adelaide Institute for Sleep Health at Flinders University and Brain and Mind Centre at the University of Sydney.

Read the paper: Improvements in Cognitive Function and Quantitative Sleep EEG in OSA after Six Months of CPAP Treatment.