MRI data show how sleep apnea damages the brain
Oxygen deprivation during certain sleep cycles could have significant implications for neural health, according to new imaging data.
A new paper in Neurology, published by researchers from the University of California, Irvine, details findings that suggest obstructive sleep apnea during the rapid-eye-movement stage of sleep could be causing damage to parts of the brain that control memory and cognition. The team believes their study provides evidence supporting the notion that sleep disturbances may be linked to early cognitive decline.
“Sleep apnea is important because low oxygen levels during sleep can harm the ability of our brain and bodies to function properly,” co-author Bryce A. Mander, PhD, assistant professor of psychiatry and human behavior at UC Irvine, said in a news release. “Our study found that low oxygen levels from obstructive sleep apnea may be linked to cognitive decline due to damage to the small blood vessels in the brain and the downstream impact of this damage on parts of the brain associated with memory.”
The findings come from the Biomarker Exploration in Aging, Cognition and Neurodegeneration study, which utilized MR imaging to track white matter hyperintensities and other structural damage of the brain. For the study, experts had a group of 37 people—24 with obstructive sleep apnea—undergo advanced brain imaging during an overnight sleep study, the results of which were compared alongside participants’ sleep apnea severity.
On imaging, the sleep apnea group displayed significantly more white matter hyperintensities, with the frontal and parietal lobes harboring the most abnormalities. They also showed thinning in the entorhinal cortex, which has been linked to neurodegeneration seen in Alzheimer’s disease.
The frontal and parietal lobes are regions of the brain that are especially active during REM sleep. This makes them especially vulnerable to damage from low oxygen. With the frontal lobe being responsible for cognitive function and memory, and the parietal lobe controlling sensory processing, experts caution that damage to these areas could have long-lasting effects of memory and cognition.
“REM sleep is when your brain does some of its most important cleanup and memory storage work,” said co-author Destiny E. Berisha, a doctoral researcher in neurobiology and behavior at UC Irvine. “If oxygen levels drop during that time, we may be interrupting critical maintenance for the brain’s memory systems.”
Of note, the team’s focus on REM sleep centered on oxygen levels, not the specific number of times individuals stopped breathing while asleep, which typically determines apnea-hypopnea index scores. These scores are used to guide providers in diagnosing the severity of an individual’s sleep apnea, but the study's findings bring that method into question.
“This is important, because we often rely on this to determine treatment,” Mander said. “Our findings show that focusing solely on the number of breathing events may miss the true physiological harm being done—especially during REM sleep.”
Although the researchers acknowledge that more research on larger sample sizes is needed, they believe their findings add to the mounting evidence implicating sleep apnea in neurodegeneration and potentially provide new information that could help providers initiate preventive treatment.
In addition to her background in journalism, Hannah also has patient-facing experience in clinical settings, having spent more than 12 years working as a registered rad tech. She began covering the medical imaging industry for Innovate Healthcare in 2021.