If you have sleep apnea and have woken up feeling like you just couldn’t think straight, there may be something to that. The effects of sleep apnea of the brain are real, measurable, and potentially serious. Here’s what you should know.
Sleep apnea and the brain
Sleep apnea affects an estimated 25 million people in the U.S. Even with these high numbers, researchers agree that this condition is under diagnosed.
The most common type of sleep apnea is obstructive sleep apnea (OSA). This condition occurs when the throat muscles and tongue relax down and back during sleep, blocking the airway. The brain notices the lack of oxygen and reflexively wakes the sleeper with a gasping intake of breath. These gasping breaths are apneas.
While a poor night of sleep is the most noticeable effect of sleep apnea, there are other health consequences. An emerging area of study is the effects of sleep apnea on the brain. Here are five recent studies highlighting the state of this research (plus some good news!).
1. Sleep apnea affects the concentration of gray matter
The American Academy of Sleep Medicine found in 2010 that otherwise healthy people with severe sleep apnea have a reduced amount of gray matter concentration in their brain. Gray matter occurs in the cerebral cortex, the information processing part of the brain.
Principal investigator Seung Bong Hong, MD, PhD, professor of neurology at the Samsung Medical Center in Sungkyunkwan University School of Medicine in Seoul, South Korea, pointed out that this reduced gray matter concentration may be responsible for more than just a shaky memory:
“Poor sleep quality and progressive brain damage induced by OSA could be responsible for poor memory, emotional problems, decreased cognitive functioning, and increased cardiovascular disturbances.”
2. Sleep apnea changes your brain chemistry
Reduced gray matter concentration is not the only change that occurs in the brain.
Researchers at the UCLA School of Nursing found low gamma-aminobutyric acid (GABA) and high glutamate in the insular cortex of the brain of those with sleep apnea. These two chemicals act as both a brake (GABA) and an accelerator (glutamate) for emotions. GABA is associated with good mood and calm. Glutamate is a stress accelerator that can be toxic when it occurs at high levels for extended periods of time.
These chemical changes in the brain are important discoveries in terms of potential treatments to counteract the effects of sleep apnea on brain chemistry.
3. Sleep apnea interferes with treatment for depression
Research now shows that sleep apnea may interfere with depression treatment.
A 2019 study examined the occurrence of undiagnosed sleep apnea in suicidal patients with major depressive disorder (MDD). The study indicated that when a person is being treated for depression, especially MDD or other types of treatment resistant depression, a sleep apnea diagnosis can be a crucial part of treatment.
4. There is a link between sleep apnea and dementia
Dementia is a disease that affects nearly six million people in the U.S. Sleep apnea and dementia are linked, and a new study found that the risk of developing the most common kind of dementia, Alzheimer’s disease, may increase risk in people with sleep apnea.
Researchers at the American Academy of Neurology found an increase of tau in the brains of patients with sleep apnea. This is important because tau is a biomarker found in excessive amounts in the brain of Alzheimer’s patients.
Study author Diego Z. Carvalho, MD, of the Mayo Clinic in Rochester, Minnesota and a member of the American Academy of Neurology, was quick to point out that it was important to untangle which condition fed the other. He notes:
“Our research results raise the possibility that sleep apnea affects tau accumulation. But it’s also possible that higher levels of tau in other regions may predispose a person to sleep apnea, so longer studies are now needed to solve this chicken and egg problem.”
5. Sleep apnea brain fog means gaps in memory
A new study found that sleep apnea can actually lead to gaps in memory.
Lead investigator Dr. Melinda Jackson of RMIT University in Melbourne, Australia found that people with sleep apnea struggled to recall even simple autobiographical memories. She found that this could lead to an increased risk of depression, especially in older patients.
Dr. Jackson notes:
“Our study suggests sleep apnea may impair the brain’s capacity to either encode or consolidate certain types of life memories, which makes it hard for people to recall details from the past. Sleep apnea is also a significant risk factor for depression so if we can better understand the neurobiological mechanisms at work, we have a chance to improve the mental health of millions of people.”
The good news: the damage can be reversible
Finally, a collaborative study using neuroimaging to look at the effects of sleep apnea treatment on brain damage found significant improvements in the brain after just three months of treatment.
Gray matter was significantly improved. White matter, the deeper tissues of the brain responsible for a variety of complex signaling and processing tasks, took longer to recover but also showed improvement.
Simply put, the effects of sleep apnea on the brain are real, but they can be treated. At AZ Dentist, we help our patients manage their sleep apnea with oral appliance therapy. An oral appliance can adjust a person’s jaw to keep their airway open during sleep.