Robert Herpen, MA , 2025-05-12 18:00:00
Key takeaways:
- Reduced oxygen during REM sleep may lead to white matter damage in the brain.
- The researchers said the results call for a renewed discussion about sleep apnea screening and treatment in older adults.
Reduced oxygen during REM sleep was associated with cerebrovascular damage in areas of the brain associated with memory and recall, which may lead to deficiencies even in cognitively healthy older adults, data show.
“It has remained a mystery why sleep apnea results in memory problems and increases risk for dementia,” Destiny E. Berisha, BS, a doctoral candidate in the department of neurobiology and behavior in the School of Biological Sciences at the University of California, Irvine, told Healio.
Data were derived from Berisha DE, et al. Neurology. 2025;doi:10.1212/WNL.0000000000213639.
“This is important, because knowing the underlying causes of memory impairments may reveal new treatment targets to reduce dementia risk in older people,” Berisha said.
As the associations between obstructive sleep apnea (OSA), the burden of cerebral small vessel disease (CSVD) and their combined effect on medial temporal lobe (MTL) structure and function are not well understood, Berisha and colleagues sought to examine whether CSVD burden is a mitigating factor linking OSA to MTL degeneration and impaired memory.
Their observational polysomnographic study included 37 cognitively unimpaired adults (mean age, 72.5 years; 62.1% women) from the Biomarker Exploration in Aging, Cognition and Neurodegeneration cohort. Eligible participants had no record of either neurologic or psychiatric disorders and were not currently taking sleep-affecting medications.
All participants underwent an MRI and had their emotional mnemonic discrimination ability assessed before and after an in-lab, overnight sleep session. The MRI was used to determine white matter hyperintensity (WMH) volumes and MTL structures along with relative thickness of the entorhinal cortex (ERC).
The researchers analyzed variables related to sleep apnea such as apnea-hypopnea index (AHI), total arousal index and a Hypoxemia Severity Index where lower SpO2 indicated more severe hypoxemia.
A total of 24 participants were diagnosed with OSA and two more with central sleep apnea.
According to results, greater global WMH volume was associated with higher AHI (r = 0.38), while hypoxemia measures significantly predicted global WMH volume with the greatest severity recorded during REM sleep.
Data additionally show that greater frontal WMH burden was an indirect influence on the association between hypoxemia during REM sleep and ERC thickness (indirect effect = 0.043, 95% CI 0.1174 to 0.00015); subsequently, the researchers found, lessened ERC thickness was linked to worse overnight memory.
These associations suggest how OSA leads to aging-related cognitive decline through degeneration of neural pathways that preserve memory in sleep, Berisha and colleagues wrote.
“Although REM sleep makes up only a quarter of the night, oxygen dips during this stage may be especially harmful to brain health in older adults,” Berisha said. “These findings call for a renewed clinical discussion about sleep apnea screening and treatment recommendations in older adults at risk for dementia.”
Reference:
Study links REM sleep apnea to brain changes, memory loss in older adults. https://news.uci.edu/2025/05/07/study-links-rem-sleep-apnea-to-brain-changes-memory-loss-in-older-adults/. Published May 7, 2025. Accessed May 8, 2025.
For more information:
Destiny E. Berisha, BS, can be reached at dberisha@uci.edu.
