Untreated Sleep Apnea May Significantly Raise the Risk of Parkinson’s Disease, But CPAP Use Can Lower It

A major new study has uncovered a striking link between untreated obstructive sleep apnea (OSA) and a significantly higher risk of developing Parkinson’s disease. The research, conducted by teams at Oregon Health & Science University (OHSU) and the Portland VA Health Care System, analyzed one of the largest patient datasets ever used in this area: electronic health records from more than 11 million U.S. military veterans who received care through the Department of Veterans Affairs between 1999 and 2022.

The findings suggest that people living with sleep apnea—especially those who avoid treatment—may face a noticeably increased risk of Parkinson’s over the long term. At the same time, the results also show something encouraging: using continuous positive airway pressure (CPAP), the standard therapy for sleep apnea, is associated with a substantial reduction in that risk.

Below is a clear, detailed breakdown of everything the study uncovered, why it matters, and what the science currently suggests about the relationship between sleep apnea and neurological health.

The Full Scope of the Study

The research team examined health records from more than 11 million veterans, an unusually large sample size for neurological studies. Out of this massive population, millions were diagnosed with obstructive sleep apnea, giving the researchers a robust group to analyze for long-term neurological outcomes.

OSA is a condition in which a person’s breathing repeatedly stops and restarts during sleep. These interruptions can cause drops in blood oxygen, fragmented sleep, and stress on various systems throughout the body—including the brain. Because Parkinson’s disease is associated with the gradual dysfunction and death of specific brain cells, researchers have long wondered whether chronic sleep issues might play a role in increasing susceptibility.

The new study shows that the connection is stronger than previously recognized. After adjusting for typical confounding variables such as age, obesity, and high blood pressure, individuals with untreated sleep apnea were found to be nearly twice as likely to develop Parkinson’s disease as those who used CPAP regularly.

Why Untreated Sleep Apnea Might Increase Parkinson’s Risk

Although the study does not claim that untreated OSA directly causes Parkinson’s, it presents a strongly suggestive association. The research team emphasizes that chronic oxygen deprivation during sleep can disrupt the functioning of neurons, especially over long periods.

Night after night, year after year, insufficient oxygen can impair how brain cells recover, regulate waste products, and maintain healthy signaling patterns. Over time, these disruptions may contribute to neurodegeneration.

Because Parkinson’s disease is characterized by the breakdown of dopamine-producing neurons in a region called the substantia nigra, any condition that reduces oxygen supply or increases cellular stress may theoretically amplify the risk of this kind of degeneration.

Researchers note that OSA may not only cause intermittent hypoxia but also promote chronic inflammation and oxidative stress, both of which are implicated in Parkinson’s pathology.

CPAP Treatment Dramatically Reduces the Risk

One of the strongest messages from the study is that early treatment makes a measurable difference. Veterans who used their CPAP machines consistently had a much lower likelihood of developing Parkinson’s compared to those who did not seek treatment or abandoned CPAP therapy.

The reduction in risk was so significant that the study authors believe this could influence how clinicians think about sleep apnea—not just as a sleep disorder but as a modifiable risk factor for neurodegenerative diseases.

Many individuals struggle with CPAP at first, often due to discomfort or difficulty adjusting to airflow during the night. But the research highlights that those who stick with it often report better daytime energy, reduced fatigue, and now potentially a decreased likelihood of future neurological decline.

The authors of the study, including specialists in neurology and pathology at OHSU and the VA, say they expect these findings to impact how they counsel patients moving forward. Encouraging consistent CPAP use could become a key part of long-term neurological health strategies.

Understanding Parkinson’s Disease and Why This Research Matters

Parkinson’s disease affects roughly 1 million people in the United States, and the risk increases steadily after age 60. Because it is a progressive condition with no cure, identifying preventable or modifiable risk factors is considered one of the most important priorities in modern neurology.

The possibility that untreated OSA may increase Parkinson’s risk opens the door to new approaches in prevention. Sleep apnea is incredibly common, especially in middle-aged and older adults, and millions of cases remain undiagnosed.

If further research confirms a causal connection, early diagnosis and treatment of OSA could become a vital part of lowering the national burden of Parkinson’s disease.

Additional Background: What Exactly Is Obstructive Sleep Apnea?

Since the study centers around OSA, it’s worth briefly explaining the condition more clearly.

Obstructive sleep apnea occurs when throat muscles relax and block the airway during sleep. The result is repeated drops in oxygen levels and abrupt awakenings—sometimes hundreds of times per night.

Common symptoms include:

Loud snoring
Daytime sleepiness
Poor concentration
Morning headaches
Dry mouth or sore throat upon waking

Factors that raise the risk of OSA include obesity, age, male sex, family history, and certain anatomical features such as a narrow airway.

Despite being widespread, it often goes undetected because the person experiencing it may have no memory of waking up throughout the night.

Additional Background: What Researchers Know About Sleep and Brain Health

Sleep quality plays a fundamental role in brain function, particularly in:

Clearing metabolic waste from neural tissue
Consolidating memories
Regulating mood and cognitive performance
Maintaining healthy oxygen and glucose levels

Chronic disruptions to sleep architecture—such as those caused by OSA—can disturb these processes. This has led to growing interest in the connection between sleep disorders and diseases like Alzheimer’s, Parkinson’s, and other forms of cognitive decline.

While not all sleep disturbances directly cause neurodegenerative disease, the accumulating evidence suggests that sleep health may be more important to long-term neural resilience than previously recognized.

The new OHSU/VA study adds considerable weight to this evolving field of research.

What Comes Next in the Research World

Experts involved in the study believe the next step is to conduct prospective, controlled research to determine whether treating sleep apnea can actively prevent the onset of Parkinson’s. Because the current study is observational, it cannot establish direct causality.

More work is also needed to:

Understand the biological mechanisms linking OSA to neurodegeneration
Explore whether similar patterns appear in younger, more diverse populations
Determine how much CPAP use is required to achieve measurable protection

Still, the scale and clarity of the findings make this one of the most influential studies published on sleep and Parkinson’s in recent years.

Research Paper Reference

Obstructive Sleep Apnea, Positive Airway Pressure, and Implications of Early Treatment in Parkinson Disease (JAMA Neurology, 2025)
https://doi.org/10.1001/jamaneurol.2025.4691