One in fifteen adults suffer from sleep apnea, a disorder characterized by brief pauses in breathing that can last from a few seconds to a minute and occur 5 to 30 times an hour.
It is known that sleep apnea leads to problems in the brain – impaired concentration, impaired memory and learning ability, increased fatigue, symptoms of depression and emotional instability may appear. However, until now it has not been completely clear what exactly is disrupted in the brain due to sleep apnea.
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Neuroscientist Paul Macey (Paul Macey) from the University of California at Los Angeles (USA) together with colleagues conducted a study that involved 14 patients suffering from obstructive sleep apnea syndrome, as well as 22 healthy volunteers. Using the so-called magnetic resonance spectroscopy, the scientists measured the levels of the neurotransmitters GABA (gamma-aminobutyric acid) and glutamate in the insular region of the subjects’ brains.
GABA is an inhibitory neurotransmitter and has a calming effect. Glutamate is the opposite of GABA in its action – it is an excitatory neurotransmitter. However, excessive levels of glutamate can increase stress levels and have toxic effects on neurons.
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Researchers have found increased levels of glutamate and reduced concentrations of GABA in the brain insula of sleep apnea patients. They were surprised at how different the concentrations of these substances in a given area of the brain were between sleep apnea patients and healthy volunteers.
“We rarely see such large differences when measuring biological parameters. We expected to find elevated levels of glutamate because we know that excess glutamate can damage the brain, and we have already seen this damage in sleep apnea. However, we were surprised by the decrease in GABA concentration. We realized that there was a reorganization of the functioning of the brain,” says Paul Macy.
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The scientist adds that these results can be called encouraging, and believes that the detected changes are reversible. In the future, the researchers plan to test how the treatment of sleep apnea (the standard treatment is the so-called CPAP therapy: using a special device to maintain constant air pressure in the airways) affects the balance of neurotransmitters in the insular zone of the brain. If these treatments fail, another option is mindfulness meditation exercises, which can provide a calming effect and possibly reduce excess glutamate levels.
Подробнее см. Р. Macey et al. «Obstructive sleep apnea is associated with low GABA and high glutamate in the insular cortex», Journal of Sleep Research, February 2016.