Sleep apnea affects an estimated 39 million adults in the U.S., yet most people don’t know they have it. It’s often dismissed as just loud snoring or poor sleep. But behind those nightly pauses in breathing is a ripple effect of oxygen loss, brain stress, and long-term health damage.
Now, a major new study involving over 11 million U.S. veterans reveals that untreated sleep apnea is tied to a significantly higher risk of developing Parkinson’s disease, a condition with no known cure.
But, starting CPAP therapy within two years of diagnosis may reduce that risk. This isn’t just a sleep issue anymore. It’s a brain health issue.
The Sleep Apnea/Parkinson’s Study:
A large-scale 2025 study conducted by researchers from the VA Portland and Puget Sound Health Care Systems has revealed a significant association between obstructive sleep apnea (OSA) and an increased risk of Parkinson’s disease (PD) (1). Drawing on over 20 years of electronic health record (EHR) data from more than 11 million U.S. military veterans, the study offers the strongest evidence to date that sleep apnea may be more than just a sleep disorder. It could be a modifying factor in neurodegeneration.
Key findings:
- Veterans diagnosed with OSA (ICD-10 code G47.33) had a significantly higher incidence of PD compared to those without OSA.
- Specifically, there were 1.8 additional cases of PD per 1,000 people within 5 years of OSA diagnosis (95% CI: 1.4–2.3; p < 0.001).
- These findings remained robust after adjusting for critical variables, including age, sex, race, smoking status, and death as a competing risk.
This suggests a potential causal link, though the study is correlational, between OSA and the development of Parkinson’s. OSA may contribute to brain inflammation, hypoxia-related oxidative stress, and protein misfolding, mechanisms already implicated in Parkinson’s disease pathology.
Importantly, the study didn’t stop at identifying risk. It also explored how the timing of CPAP therapy, a common treatment for OSA, impacts the progression to Parkinson’s. That’s where the findings become even more actionable for clinicians and patients.
How Does CPAP Work to Protect the Brain?
Continuous Positive Airway Pressure (CPAP) therapy is the first-line treatment for OSA. It delivers a steady stream of air through a mask during sleep, keeping the airway open and preventing apneic events. But this isn’t just about better sleep. In the context of Parkinson’s prevention, CPAP may be doing something much deeper, preserving neurological integrity.
The study divided participants with OSA into three groups:
- CPAP+ Early (CPAP started within 2 years of OSA diagnosis)
- CPAP+ Late (CPAP started more than 2 years after diagnosis)
- CPAP- (no documented CPAP usage)
Results showed:
Veterans in the CPAP+ Early group had a 2.3-case reduction in PD incidence per 1,000 people at 5 years post-OSA diagnosis (p < 0.001). In contrast, those in the CPAP+ Late group showed no significant difference in PD risk compared to those who never used CPAP.
Mechanisms behind CPAP’s brain-protective effects likely include:
- Restoration of oxygen flow to the brain, minimizing the repeated hypoxia episodes that damage brain tissue.
- Reduction in systemic inflammation, a known contributor to neurodegenerative conditions.
- Improved sleep architecture, especially deep sleep stages where the brain performs waste clearance through the glymphatic system, essential for removing neurotoxic proteins like alpha-synuclein, which accumulate in Parkinson’s.
In simpler terms, CPAP may slow or prevent the changes in the brain that lead to Parkinson’s, but only if it’s started early, while those changes are still reversible or at least modifiable.
What Are the Risks of Untreated Sleep Apnea?
OSA isn’t just snoring or daytime drowsiness. Left untreated, it’s a chronic condition with multi-system consequences. And when it comes to Parkinson’s, ignoring OSA could mean accelerating brain decline years before clinical symptoms even appear.
Evidence-backed risks of untreated sleep apnea include:
- Cardiovascular disease – People with OSA are 2 to 3 times more likely to develop hypertension, heart failure, atrial fibrillation, and stroke.
- Cognitive impairment – Chronic sleep disruption and oxygen deprivation contribute to memory loss, attention problems, and executive dysfunction.
- Mood disorders – OSA is associated with higher rates of depression and anxiety, which may in turn worsen sleep and increase Parkinson ‘s-related symptom burden.
- Insulin resistance and type 2 diabetes – Sleep apnea increases inflammation and cortisol levels, both of which impair glucose regulation.
- Early mortality – Studies consistently link untreated OSA to higher all-cause mortality, largely due to its effects on the heart and brain.
Add to this new research a substantially higher risk of developing Parkinson’s disease. In other words, sleep apnea affects your long-term neurological health, potentially years before PD symptoms emerge.
Can Sleep Apnea Treatment Reverse the Effects of Parkinson’s Disease?
The short answer: No, CPAP cannot reverse Parkinson’s once it develops. But the more accurate answer is nuanced and hopeful.
Parkinson’s disease is a progressive neurodegenerative condition. Once dopamine-producing neurons in the substantia nigra are lost, they don’t regenerate. This means treatments like CPAP can’t bring those neurons back. However, that doesn’t mean CPAP is powerless.
CPAP can still offer important benefits for individuals who already have Parkinson’s:
- Improved sleep quality, which may alleviate symptoms such as fatigue, tremor exacerbation, and mood swings.
- Better cognitive function, due to more stable oxygen levels and reduced nighttime awakenings.
- Reduced daytime sleepiness, helping to maintain independence and quality of life.
- Fewer falls and accidents, as sleep deprivation and postural instability are compounded in PD.
Most crucially, early CPAP therapy, started before Parkinson’s symptoms begin, may reduce the likelihood of ever developing PD. According to the 2025 study, this preventative potential is lost if CPAP is delayed beyond two years after OSA diagnosis.
Why Should You Get Screened for Sleep Apnea?
Screening for sleep apnea can save your life and protect your brain, heart, and quality of living. Obstructive sleep apnea (OSA) is a serious sleep disorder that often goes undiagnosed, yet it affects an estimated 39 million adults in the United States, according to the American Academy of Sleep Medicine. Even more concerning, up to 80% of moderate to severe cases remain undiagnosed. That’s a public health crisis hiding in plain sight.
Many people assume snoring is harmless. It’s not. Loud, chronic snoring, especially when paired with gasping, choking, or daytime fatigue, is often the first red flag of OSA. But the condition does far more than disrupt sleep. It causes repeated episodes of oxygen deprivation throughout the night, damaging blood vessels, increasing blood pressure, and harming brain cells.
Left untreated, OSA significantly increases the risk of:
- Hypertension (up to 3x more likely)
- Heart disease
- Stroke
- Type 2 diabetes
- Cognitive decline and memory loss
- Depression and anxiety
- Motor vehicle and workplace accidents
And now, research confirms a new and alarming link: untreated sleep apnea increases the risk of developing Parkinson’s disease, a neurodegenerative disorder with no cure. However, early treatment with CPAP reduced that risk when started within two years of diagnosis.
That’s why early screening matters. You may feel fine now, but sleep apnea is insidious. Many patients don’t realize they stop breathing during the night, sometimes dozens to hundreds of times per hour. Over time, this chronic strain takes a heavy toll on your organs and cognition.
You should especially consider a sleep apnea screening if you:
- Snore loudly or gasp during sleep
- Wake up tired even after a full night
- Suffer from morning headaches or dry mouth
- Have trouble concentrating or remembering things
- Are overweight or have a large neck circumference
- Have high blood pressure or heart disease
- Have a family history of sleep apnea or neurodegenerative disease
Fortunately, sleep apnea is highly treatable. The gold standard is CPAP therapy, which keeps airways open, improves oxygen flow, and helps restore restorative sleep. For those who can’t tolerate CPAP, other options exist like oral appliances, lifestyle changes, and even implantable treatment like Inspire.
But none of those treatments can happen without a diagnosis. A sleep study, whether in a lab or at home, is noninvasive and could be life-changing.
In short, sleep apnea affects your heart, brain, and future. Getting screened is a small step with massive benefits. The earlier you act, the more you can protect.
The Insomnia and Sleep Institute of Arizona Can Help You Manage Your Sleep Apnea and Related Risks
The Insomnia and Sleep Institute of Arizona is the state’s leading center for sleep medicine. Backed by board-certified sleep physicians, nationally recognized expertise, and years of clinical excellence, our team treats both adults and children as young as one year old.
From accurate diagnostics to advanced therapies like CPAP and Inspire implants, every step is guided by proven science and outstanding patient outcomes. Named “Top Docs” eight years in a row and awarded for care excellence by Inspire, we consistently lead the field. Reach out today to schedule a consultation.
References
- Montano, I., May, J., Neilson, L., Cho, Y., Iliff, J., Elliott, J., Scott, G., & Lim, M. (n.d.). EMBARGOED FOR RELEASE UNTIL 4 P.M. ET, SUNDAY, MARCH 2, 2025 Abstract Title: Obstructive Sleep Apnea is a Risk Factor for Parkinson’s Disease and CPAP Mitigates Risk of PD: An EHR-based Cohort Study in Military Veterans Press Release Title: Sleep apnea linked to increased risk of Parkinson’s, but CPAP may reduce risk Risk reduced if treatment started within two years of diagnosis. [email protected], 612, 283–5484. Retrieved April 5, 2025, from https://aanfiles.blob.core.windows.net/aanfiles/1bfbec30-cc5c-4160-8640-87819116ef56/2025%20AAN%20Annual%20Meeting%20Abstract%20-%20Obstructive%20Sleep%20Apnea%20and%20Parkinson%27s%20Disease
Disclaimer: The information provided in this blog post is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always consult with a licensed healthcare provider for recommendations specific to your individual health needs.
