By Janice Wood
A new study shows that people with sleep apnea show significant changes in the levels of two important brain chemicals.
This could be the reason so many people with sleep apnea — a disorder in which a person’s breathing is frequently interrupted during sleep, as many as 30 times an hour — report problems with thinking, such as poor concentration, difficulty with memory and decision-making, depression and stress.
Researchers at the University of California Los Angeles School of Nursing looked at levels of the neurotransmitters glutamate and gamma-aminobutyric acid, known as GABA, in a brain region called the insula. This area integrates signals from higher brain regions to regulate emotion, thinking, and physical functions, such as blood pressure and perspiration.
They found that people with sleep apnea had decreased levels of GABA and unusually high levels of glutamate.
GABA is a chemical messenger that acts as an inhibitor in the brain, which can slow things down and help keep people calm. It affects mood and helps make endorphins, researchers explain.
Glutamate, by contrast, is like an accelerator. When glutamate levels are high, the brain is working in a state of stress, and consequently doesn’t function as effectively. High levels of glutamate can also be toxic to nerves and neurons, the researchers noted.
“In previous studies, we’ve seen structural changes in the brain due to sleep apnea, but in this study we actually found substantial differences in these two chemicals that influence how the brain is working,” said Dr. Paul Macey, the lead researcher on the study and an associate professor at the University of California, Los Angeles School of Nursing.
Macey said the researchers were taken aback by the differences in the GABA and glutamate levels.
“It is rare to have this size of difference in biological measures,” he said. “We expected an increase in the glutamate, because it is a chemical that causes damage in high doses and we have already seen brain damage from sleep apnea. What we were surprised to see was the drop in GABA. That made us realize that there must be a reorganization of how the brain is working.”
He added that the study’s results are actually encouraging.
“In contrast with damage, if something is working differently, we can potentially fix it,” he said.
“What comes with sleep apnea are these changes in the brain, so in addition to prescribing continuous positive airway pressure, or CPAP, physicians now know to pay attention to helping their patients who have these other symptoms,” he continued. “Stress, concentration, memory loss — these are the things people want fixed.”
A CPAP machine helps an individual sleep easier, and is considered the gold standard treatment for sleep disturbance.
In future studies, the researchers said they hope to determine whether treating sleep apnea using CPAP or other methods returns patients’ brain chemicals back to normal levels.
If not, they will turn to the question of what treatments could be more effective. The researchers said they are also studying the impacts of mindfulness exercises to see if they can reduce glutamate levels by calming the brain.
The study, conducted at the University of California, Los Angeles Sleep Disorder Center, was published in the Journal of Sleep Research.