Alzheimer’s disease and other forms of dementia affect memory, thinking and everyday life. While some risk factors—like age and family history—cannot be changed, others can. One important and treatable risk factor is obstructive sleep apnea.

Obstructive sleep apnea (OSA) is a common condition in which breathing repeatedly stops and starts during sleep. Research shows that untreated sleep apnea may increase the risk of memory problems, cognitive decline and dementia, including Alzheimer’s disease. The good news is that treating sleep apnea may help protect brain health.

What is obstructive sleep apnea?

During sleep, the muscles in the back of the throat relax. In people with obstructive sleep apnea, these muscles relax too much and block the airway. Breathing briefly stops, and the brain wakes the person up just enough to breathe again.

According to Nebraska Medicine neurologist Daniel Murman, MD, this cycle can happen dozens or even hundreds of times each night. Even though a person may stay in bed for six to eight hours, the sleep is broken and not restful.

Symptoms of sleep apnea

Many people do not realize they have sleep apnea. Common warning signs include:

• Loud, chronic snoring.
• Pauses in breathing during sleep, often noticed by a bed partner.
• Snorting or gasping during the night.
• Excessive daytime sleepiness.
• Trouble concentrating or staying focused.
• Morning headaches or feeling unrefreshed after sleep.

In more severe cases, breathing pauses can lower oxygen levels during sleep. This lack of oxygen can harm multiple organs, including the brain.

How sleep apnea affects the brain

Untreated sleep apnea affects the brain in both the short and long term.

“In the short term, disrupted sleep makes it harder to think clearly,” says Dr. Murman. “People may struggle with attention, multitasking, reaction time and memory. These symptoms can look like early dementia but may improve with treatment.”

Over time, repeated drops in oxygen and poor-quality sleep may cause lasting changes in the brain. Multiple studies show a strong link between untreated sleep apnea and a higher risk of:

• All types of dementia.
• Alzheimer’s disease.
• Vascular (blood vessel–related) cognitive decline.

While research continues, scientists believe there are several ways sleep apnea may contribute to brain damage:

Reduced oxygen to the brain: Repeated drops in oxygen can injure brain cells, especially in areas involved in memory.

Damage to small blood vessels: Sleep apnea is linked to changes in the brain’s small blood vessels. These changes may lead to tiny areas of bleeding or reduced blood flow, which are associated with memory loss and cognitive decline.

Disruption of the brain’s cleaning system: During deep sleep, the brain removes waste products, including abnormal proteins linked to Alzheimer’s disease. Because sleep apnea prevents deep sleep, this cleanup process may not work as effectively, allowing harmful proteins to build up over time.

Sleep apnea is a treatable cause of memory problems

Doctors often see patients—sometimes in their 50s or 60s—who report memory problems, trouble focusing or mental fog. “In many cases, the main cause is untreated sleep apnea rather than a permanent form of dementia,” says Dr. Murman. “Treating sleep apnea can significantly improve thinking and memory in these individuals.”

Because sleep apnea is reversible and treatable, it is an important condition to evaluate in anyone experiencing cognitive changes.

How sleep apnea is diagnosed

Sleep apnea can be screened by a primary care provider or sleep disorder specialist. Common testing options include:

• Home sleep studies: Measure breathing, oxygen levels and sleep at home.
• In-lab sleep studies: Done at a sleep center for more detailed testing.

For many people with typical symptoms, a home sleep test is enough to make a diagnosis.

Treatment options for sleep apnea

Treating sleep apnea improves sleep quality, daytime alertness and overall health—and may help protect the brain.

Common treatments include:

• CPAP (continuous positive airway pressure): A machine that keeps the airway open during sleep using gentle air pressure.
• Oral appliances: Custom mouthpieces that hold the jaw forward, often used for mild to moderate sleep apnea.
• Weight loss: Even modest weight loss can reduce sleep apnea severity for some people.
• Positional therapy: Changing your sleep position by not sleeping on your back can reduce sleep apnea.
• Implantable devices: Such as Inspire® therapy, for certain patients who cannot tolerate CPAP.

Your care team can help determine which option is best for you.

Why treating sleep apnea matters

Treating obstructive sleep apnea may:

• Improve memory, focus and thinking.
• Reduce the risk of dementia and Alzheimer’s disease.
• Protect heart and blood vessel health.
• Improve diabetes control.
• Reduce daytime sleepiness and improve safety, including driving.

“While research is ongoing, many studies suggest that untreated sleep apnea may speed up cognitive decline,” says Dr. Murman. “Treating it offers benefits now and may help protect brain health in the future.”

When to seek help

If you or a loved one has loud snoring, breathing pauses during sleep, excessive daytime sleepiness or changes in memory or thinking, it’s important to seek evaluation. Early diagnosis and treatment may make a meaningful difference.