• Obstructive sleep apnea is linked to brain damage in areas critical for memory, especially during REM sleep due to low oxygen levels.
• Brain damage is associated with white matter hyperintensities, reduced volume in the hippocampus and entorhinal cortex, and poorer sleep-dependent memory.
• The findings suggest a potential mechanism for how sleep apnea contributes to cognitive decline and Alzheimer's disease.

A new study published in Neurology on May 7, 2025, reveals a link between obstructive sleep apnea and damage to brain regions associated with memory. The study, involving 37 participants with an average age of 73, found that lower oxygen levels during REM sleep were associated with higher levels of white matter hyperintensities, indicating damage to small blood vessels in the brain. This damage correlated with reduced volume in the hippocampus and entorhinal cortex, both crucial for memory, and was linked to poorer performance on memory tests. The research suggests that sleep apnea may contribute to cognitive decline and memory loss.

• What: Obstructive sleep apnea is linked to brain damage, particularly in the hippocampus and entorhinal cortex, which are critical for memory. This damage is likely due to low oxygen levels during REM sleep, causing white matter hyperintensities.
• Who: The study involved 37 participants with an average age of 73, 24 of whom had obstructive sleep apnea. The lead researcher is Bryce A. Mander, PhD, of the University of California Irvine.
• When: The study was published online in Neurology on May 7, 2025. Participants underwent overnight sleep studies and took memory tests before and after sleep.
• Where: The research was conducted at the University of California Irvine.

This study provides valuable insight into the potential long-term effects of obstructive sleep apnea on brain health. The correlation between low oxygen levels during REM sleep, brain damage, and memory impairment suggests a pathway through which sleep apnea may contribute to cognitive decline and Alzheimer's disease. While the study does not prove causation, the findings highlight the importance of addressing sleep apnea, especially in older adults. The limitation noted by the researchers, that the study participants were primarily white and Asian, suggests that future research should include a more diverse population.

Our study found that low oxygen levels from obstructive sleep apnea, especially during REM sleep, 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.

Taken together, our findings may partially explain how obstructive sleep apnea contributes to cognitive decline associated with aging and Alzheimer’s disease through the degeneration of brain regions that support memory consolidation during sleep

The study offers compelling evidence linking obstructive sleep apnea to brain damage and memory loss. The findings suggest that addressing sleep apnea could be crucial in mitigating cognitive decline and the risk of Alzheimer's disease. Further research is needed to confirm these findings in more diverse populations and to explore potential interventions to prevent or reverse the brain damage associated with sleep apnea.