Researchers found veterans with the sleep disorder were nearly twice as likely to later develop Parkinson’s disease

Sleep apnoea - undiagnosed in an estimated 80% of cases - causes serious health complication, including elevated risk of a stroke, plus practical problems including daytime tiredness and loud snoring. Researchers have found a potential link to the development of Parkinson’s disease. Photo / Getty Images

Researchers have found a potential link between obstructive sleep apnoea and the development of Parkinson’s disease, according to a new study.

Obstructive sleep apnoea - a disorder in which a person experiences a fully or partially collapsed airway during sleep, causing a lack of oxygen and non-restorative rest - affects millions of people and often goes undiagnosed, according to the American Medical Association.

Parkinson’s disease, an incurable progressive movement disorder, is the second-most common neurodegenerative disorder in the United States and is thought to affect about 1.1 million people.

In the study, published in the journal JAMA Neurology yesterday, researchers combed through the health records of more than 11 million US veterans from 1999 to 2022.

Nearly 14% of them had sleep apnoea, and those with the disorder were nearly twice as likely to have developed Parkinson’s six years after those diagnoses.

Among those who treated their sleep apnoea with continuous positive airway pressure therapy - also known as CPAP - early in their diagnoses, Parkinson’s case numbers were “significantly reduced”, the study stated.

Gregory Scott, one of the study’s co-authors and an assistant professor of pathology in Oregon Health and Science University’s School of Medicine, said in a statement that obstructive sleep apnoea is “not at all a guarantee” that someone will develop Parkinson’s, “but it significantly increases the chances”.

Symptoms of sleep apnoea include snoring, gasping for air, fatigue even after a perceived full night of sleep, and frequent waking during the night.

Parkinson’s disease is associated with a long list of potential symptoms, including tremors, difficulty moving or walking, problems with balance, drooling, sleep disorders, and issues with speaking or swallowing.

Danny Eckert, an expert in obstructive sleep apnoea and a professor at Flinders University’s College of Medicine and Public Health in Australia, called it an “interesting and novel finding” that adds to a growing body of research suggesting that repeated sleep disruption - no matter the cause - “has a range of adverse outcomes”.

Another sleep condition, rapid eye movement sleep behaviour disorder, was also linked to Parkinson’s disease, he said.

“One of the cautionary notes is that it was not a randomised trial,” Eckert added. “So the people who seem to be doing better that were on CPAP therapy may just be the ones that are more likely to adapt a healthy lifestyle.”

Though the study does not prove obstructive sleep apnoea causes Parkinson’s disease, experts believe it may offer a clue to where researchers could dig further.

Kin Yuen, a sleep medicine physician and assistant clinical professor at the University of California at San Francisco, said the findings are not surprising given that poor sleep tends to be associated with worse neurological outcomes.

It also remains unclear how strong the links between obstructive sleep apnoea and Parkinson’s truly are.

However, one theory is that the “repeated lack of oxygen” caused by obstructive sleep apnoea may “impair the brain’s ‘repair’ during sleep”, she said in an email.

“Clinically, patients with Parkinson’s syndrome or disease are often seen in sleep clinics because of comorbid obstructive sleep apnoea,” Yuen added.

Lee Neilson, the study’s lead author and an assistant professor of neurology at Oregon Health and Science University, offered a similar theory.

“If you stop breathing and oxygen is not at a normal level, your neurons are probably not functioning at a normal level either,” he said.

“Add that up night after night, year after year, and it may explain why fixing the problem by using CPAP may build in some resilience against neurodegenerative conditions, including Parkinson’s.”

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