This Common Sleep Issue May Increase Your Risk of Alzheimer’s Disease, Study Finds
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New research shows sleep apnea may increase your risk of cognitive decline, Alzheimer’s disease, and stroke.
Sleep apnea is a sleep disorder characterized by interrupted breathing during sleep, leading to interrupted sleep, frequent awakenings and a lack of restful slumber.
Experts explain the findings and the importance of diagnosis and treatment of sleep apnea.
If you happen to snore or often wake up suddenly in the night, you could have sleep apnea. While snoring is often thought to be of little concern, new research shows that sleep apnea could put you at an increased risk of stroke, Alzheimer’s disease, and cognitive decline.
A study recently published in Neurology involved 140 participants, with an average age of 73, from the Mayo Clinic Study of Aging. These participants did not have dementia and had undergone at least one brain MRI and polysomnogram (PSG), an overnight study in a sleep lab.
The study looked at sleep factors and biomarkers of the health of the brain’s white matter. The biomarkers measure how well the brain’s white matter is preserved, which is important to connect different parts of the brain. One of the biomarkers, white matter hyperintensities, are tiny lesions visible on brain scans. White matter hyperintensities become more common with age or with uncontrolled high blood pressure. The other biomarker measures the integrity of the axons, which form the nerve fibers that connect nerve cells.
The researchers found a potential association between sleep apnea, reduced deep sleep, and signs indicative of early cerebrovascular disease, which is associated with an increased risk of stroke, Alzheimer’s disease, and cognitive decline. They discovered that for every 10-point decrease in the percentage of slow-wave (deep) sleep, there was an increase in white matter hyperintensities (small brain lesions), similar to the effect of aging 2.3 years, and a decrease in axonal integrity (brain cell communication), similar to aging three years.
What is sleep apnea?
Sleep apnea is a sleep disorder characterized by interrupted breathing during sleep, often leading to waking up during the night and a general lack of restful sleep, says Patrick Porter, Ph.D., neuroscience expert and creator and CEO of BrainTap. “This condition can be classified as mild, moderate, or severe, depending on its severity.” People with sleep apnea often experience reduced time in deep sleep, also known as slow-wave sleep or non-REM stage 3 sleep, which is a crucial indicator of sleep quality, he explains.
How does sleep apnea affect brain health long-term?
Sleep apnea is associated with reduced oxygenation, increased adrenaline surges (as your body recognizes the lack of oxygen, and pushes you to wake up), hypertension, GERD (gastroesophageal reflux), atrial fibrillation, poor quality sleep (less deep sleep and REM sleep), and risk of cognitive decline, says Dale Bredesen, M.D., neuroscience researcher and neurodegenerative disease expert. “Thus, it is a relatively common, often undiagnosed, often under-treated, probable cause of cognitive decline in many individuals.”
Deep sleep plays a crucial role in brain restoration and memory consolidation, says Porter. “When individuals with sleep apnea spend less time in this restorative sleep stage, it can impair their cognitive function and increase the risk of cognitive decline over time,” he adds. And because sleep apnea is associated with hypertension and atrial fibrillation, those with the disorder are at increased risk of stroke, says Dr. Bredesen.
Put simply, a brain that is not well rested tends to function less well, says Amit Sachdev, M.D., director of the Division of Neuromuscular Medicine at Michigan State University. “This manifests itself as changes in decision making and mood.”
How to know if you have sleep apnea and how to treat it
As you might expect, many people discover they have sleep apnea from their partner that witnesses their interrupted sleep in the night “If there is a concern for sleep apnea, then a sleep study may help with the diagnosis,” Dr. Sachdev says.
Everyone should check their oxygen status at night (at least occasionally), and this can be done with wearables or with an oximeter (inexpensive to purchase, or you can borrow one from your practitioner), suggests Dr. Bredesen. “If there is any suspicion, obtain a sleep study, which is the gold standard for determining if you have sleep apnea.” A normal number of apneic events, or pauses in breathing, is fewer than 5 per hour of sleep, says Dr. Bredesen.
Also, note that if you wake up frequently out of breath, if you snore, if you do not feel rested when you wake up in the morning, or if you are at a higher risk based on your build (men with short necks are at high risk), you should consider a sleep study to determine your diagnosis, advises Dr. Bredesen.
If sleep apnea is diagnosed, there are several treatment options available, says Porter. “The most common and effective treatment is positive airway pressure therapy, which involves wearing a mask over the nose or nose and mouth during sleep.” This mask, also known as a CPAP machine, delivers a continuous stream of air, keeping the airways open and preventing breathing interruptions.
Additionally, lifestyle changes can significantly contribute to managing sleep apnea, adds Porter. “These may include maintaining a healthy weight, avoiding alcohol and sedatives before bedtime, sleeping in a side position instead of on your back, and establishing a consistent sleep routine.”
The bottom line
At the end of the day, brain health is all about the basics, says Dr. Sachdev: “Good sleep, stress reduction, and good diet are all important.”
Recognizing the impact of sleep apnea on these neurological conditions is crucial for early intervention and prevention, says Porter. “Prioritizing healthy sleep and seeking appropriate treatment, such as positive airway pressure therapy, can help alleviate breathing disruptions during sleep, improve sleep quality, and can potentially make a significant difference in reducing the risks of Alzheimer’s disease, cognitive decline, and stroke associated with sleep apnea.”
Sleep apnea is “one of the common contributors we see in our patients with cognitive decline, and it is often overlooked by physicians, so it’s important for patients and family members to be aware of this and discuss it with their practitioners,” adds Dr. Bredesen.
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