Sleep apnea may lead to worse brain health

A recent study led by the Mayo Clinic in Rochester, Minnesota has found that people who have sleep apnea and spend less time in deep sleep may have brain biomarkers that have been previously associated with an increased risk of Alzheimer’s disease, cognitive decline, and stroke. 

The experts examined the association between sleep factors and two types of biomarkers that provide insights into the health of the brain’s white matter (a network of nerve fibers playing a major role in connecting different areas of the brain). One of these biomarkers – known as “white matter hyperintensities” – represents tiny lesions visible on brain scans, which become more common with age or uncontrolled high blood pressure, while the other one measures the integrity of axons, which form the nerve fibers connecting neurons.

“These biomarkers are sensitive signs of early cerebrovascular disease,” said study lead author Diego Z. Carvalho, a neurologist at the Mayo Clinic. “Finding that severe sleep apnea and a reduction in slow-wave sleep are associated with these biomarkers is important since there is no treatment for these changes in the brain, so we need to find ways to prevent them from happening or getting worse.” 

The study involved 140 individuals with an average age of 73 who were diagnosed with obstructive sleep apnea, a disorder characterized by repeated episodes of complete or partial blockage of the upper airway during sleep, which leads to a reduction or cessation of breathing. 

Among these individuals, 34 percent had mild, 32 percent had moderate, and 34 percent had severe sleep apnea. None of the participants had neurodegenerative disorders before or at the end of the experiment, which consisted of a brain scan and an overnight study in a sleep lab.

The sleep study investigated how long participants spend in slow-wave sleep, which is also known as “non-REM stage 3 sleep” and is considered to be one of the best markers of sleep quality. 

The results revealed that, for every 10-point decrease in the percentage of slow-wave sleep, there was an increase in the amount of white matter hyperintensities similar to the effect of being 2.3 years older, and a reduced axonal integrity similar to the effect of being three years older. 

Moreover, participants with severe sleep apnea had a higher volume of white matter intensities and more reduced axonal integrity in the brain than those with mild or moderate cases.

Regardless of these statistically significant associations, the researchers stressed that the results do not yet prove a clear causality between sleep disturbances and brain health. 

“More research is needed to determine whether sleep issues affect these brain biomarkers or vice versa. We also need to look at whether strategies to improve sleep quality or treatment of sleep apnea can affect the trajectory of these biomarkers,” Carvalho concluded.

The study is published in the journal Neurology^®.

More about sleep apnea

Sleep apnea is a sleep disorder characterized by pauses in breathing or shallow breaths during sleep. These interruptions in breathing can last for a few seconds to minutes and may occur multiple times throughout the night. Sleep apnea can disrupt the normal sleep cycle and lead to various health issues if left untreated.

There are three main types of sleep apnea:

Obstructive Sleep Apnea (OSA)

This is the most common form of sleep apnea. It occurs when the muscles in the back of the throat fail to keep the airway open, despite efforts to breathe. The airway becomes partially or completely blocked, leading to loud snoring, gasping, or choking sounds as the person struggles to breathe.

Central Sleep Apnea (CSA)

This condition is less common and occurs when the brain fails to send proper signals to the muscles that control breathing. Unlike OSA, there is no physical blockage in the airway. People with CSA may not snore as much, but they may experience shortness of breath or difficulty initiating and maintaining sleep.

Complex/Mixed Sleep Apnea

This type of sleep apnea is a combination of both obstructive and central sleep apnea. It initially starts as central sleep apnea, but eventually, the condition progresses to include obstructive episodes as well.

Common symptoms include:

Loud, chronic snoring

Snoring is a common symptom of sleep apnea, particularly in cases of OSA. The snoring is often loud and may be interrupted by periods of silence when breathing stops.

Gasping or choking during sleep

People with sleep apnea may experience sudden awakenings accompanied by gasping or choking sensations as they struggle to breathe.

Excessive daytime sleepiness

Sleep apnea disrupts the normal sleep cycle, preventing restful sleep. As a result, individuals with this disorder often feel excessively sleepy during the day, regardless of how much sleep they get at night.

Morning headaches

Waking up with a headache is a common symptom of sleep apnea. It is typically caused by the oxygen deprivation that occurs during sleep apnea episodes.

Fatigue and daytime drowsiness

Due to the disrupted sleep patterns, individuals with sleep apnea may feel fatigued and excessively sleepy during the day, which can impact their ability to concentrate and perform daily tasks.

Difficulty concentrating and memory problems

Sleep apnea can impair cognitive function, leading to difficulties with concentration, memory problems, and decreased alertness.

Irritability and mood changes

Sleep disorders can contribute to irritability, mood swings, and even depression. The lack of quality sleep can significantly impact a person’s emotional well-being.

Frequent nighttime urination

Sleep apnea has been associated with increased nighttime urination, known as nocturia. The frequent awakenings due to breathing difficulties can disrupt the normal sleep pattern and trigger the need to urinate.

Treatment options vary depending on the severity and type of sleep apnea. Lifestyle changes such as weight loss, regular exercise, and avoiding alcohol and sedatives can help in mild cases. 

Continuous Positive Airway Pressure (CPAP) therapy is the most common treatment for moderate to severe cases. It involves wearing a mask over the nose or mouth during sleep, which delivers a constant flow of air to keep the airway open.

Other treatment options may include oral appliances that help keep the airway open, positional therapy, and surgery in certain cases.

If you suspect you or someone you know may have sleep apnea, it is important to consult a healthcare professional for a proper diagnosis and appropriate treatment.

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By Andrei Ionescu, Earth.com Staff Writer

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