In a study published Monday in JAMA Neurology, researchers linked obstructive sleep apnea, a condition that causes temporary pauses in breathing during sleep, with Parkinson’s disease.
Parkinson’s disease is a progressive nervous system disorder that causes tremors, stiffness, and difficulty speaking, moving and swallowing. It is the second-most common neurodegenerative disease in the United States, after Alzheimer’s disease, with 90,000 people diagnosed each year.
There is no cure for Parkinson’s disease, said Dr. Lee Neilson, a neurologist at Oregon Health & Science University who led the study. But the researchers did find that treating sleep apnea with a continuous positive airway pressure (or CPAP) machine was associated with a reduced likelihood of developing Parkinson’s.
So identifying those at highest risk for the neurological condition — and intervening early, Dr. Neilson said, “might make the biggest impact.”
What the study found
The researchers analyzed medical records from more than 11 million U.S. veterans treated through the Department of Veterans Affairs between 1999 and 2022. The group was predominantly male with an average age of 60, representing those at highest risk for sleep apnea, experts said.
The researchers found that about 14 percent of the participants had been diagnosed with sleep apnea between 1999 and 2022, according to their medical records. When the researchers looked at their health six years after those diagnoses, they found that the veterans with sleep apnea were nearly twice as likely to have developed Parkinson’s disease compared with those who had not been diagnosed with sleep apnea.
This held even after controlling for other factors that could influence the development of sleep apnea or Parkinson’s disease, including high body mass index and conditions like diabetes, high blood pressure, traumatic brain injuries and depression.
Those who started using CPAP machines within two years of their diagnoses were about 30 percent less likely to develop Parkinson’s disease than those who didn’t use the treatment.
CPAP machines blow air through a face mask to keep the airway open. When used correctly and consistently, the devices are effective at treating sleep apnea. But many people find them noisy or uncomfortable and don’t stick with them long enough to reap their benefits.
The study did not prove that sleep apnea caused Parkinson’s disease, nor that using CPAP machines could stave off the disease, said Dr. Sairam Parthasarathy, a physician and sleep researcher at the University of Arizona who was not involved with the new research.
Still, he said, the study was important — and to his knowledge, the largest and strongest to date suggesting the association between sleep apnea and Parkinson’s disease. He hopes it will encourage more research into the link.
Why sleep apnea might affect Parkinson’s risk
About 13 percent of Parkinson’s cases worldwide are linked to genetic mutations, and some research suggests that environmental toxins like pesticides and heavy metals might also increase the risk.
It’s not clear how sleep apnea may play a role in the condition, said Dr. Ronald Postuma, a professor of neurology at McGill University in Montreal who was not involved with the new research.
The study authors theorized that by limiting oxygen over time, sleep apnea could cause enough damage to brain cells that they no longer function properly, contributing to Parkinson’s disease.
The condition might also interfere with the brain’s waste removal system, called the glymphatic system, which operates mainly during sleep, said Dr. Gregory Scott, an assistant professor of pathology at the O.H.S.U. School of Medicine and a co-author of the study. Some scientists have said that this might also explain the connection between sleep apnea and dementia.
It will take much more research to confirm any of these theories. Still, Dr. Parthasarathy added, it makes sense that a sleep condition that regularly limits oxygen to the brain could contribute to a neurological disease like Parkinson’s.
“It’s not a pie-in-the-sky kind of finding,” he said.
If the study encourages more people to seek treatment for sleep apnea, that would be a good thing, the experts we spoke with agreed. CPAP machines “can be annoying and challenging to try,” Dr. Scott added, but their benefits can be invaluable.
Caroline Hopkins Legaspi is a Times reporter focusing on nutrition and sleep.
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