Sleep apnea, a sleep disorder characterized by pauses in breathing during sleep, has been linked to an increased risk of dementia. A new study published in the medical journal Neurology investigated the relationship between sleep apnea and brain volume.
The study involved 122 participants with an average age of 69 who did not have memory problems. Of these, 26 had amyloid plaques in their brains, which are early signs of Alzheimer’s disease. The participants underwent brain scans, memory tests, and overnight sleep studies at home.
The results showed that people with amyloid plaques who had more severe sleep apneas were more likely to have lower volumes in the medial temporal lobe area of the brain, including the hippocampus. The hippocampus plays a role in memory and is affected by Alzheimer’s disease. People without amyloid plaques did not show this connection even if they had severe sleep apnea.
The study does not prove that sleep apnea causes decreased brain volume; it only shows an association. However, it suggests that some people may be more vulnerable to the adverse effects of sleep apnea.
“Our results suggest that people in the early stages of the Alzheimer’s disease continuum showed a specific vulnerability to sleep apneas,” said Geraldine Rauchs, PhD, one of the study authors from Inserm in Caen, France. “Additional studies should look at whether treatment of sleep-disordered breathing could improve cognition and prevent or delay neurodegeneration.”
Lower volumes in the hippocampus at the start of the study were associated with lower scores on a test of episodic memory at the end of the study across all participants. There were no associations between sleep apneas at the start of the study and memory scores at its conclusion.
One limitation of this research was that participants took identical verbal learning tests both before and after 21 months. This might have minimized any decline due to familiarity with taking such tests repeatedly.
Based on the news, more studies should be conducted to investigate whether treating sleep-disordered breathing could improve cognition and prevent or delay neurodegeneration.
Reference: André C, Kuhn E, Rehel S, et al. Association of sleep-disordered breathing and medial temporal lobe atrophy in amyloid-positive older adults without cognitive impairment. IN. 2023. doi: 10.1212/WNL.0000000000207421
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