Link Between REM Sleep Apnea and Memory Decline Revealed

A recent study has established a connection between obstructive sleep apnea during rapid eye movement (REM) sleep and alterations in brain areas associated with memory. This research, published in the journal Neurology, highlights how reduced oxygen levels during sleep could lead to degeneration in brain regions critical for memory function.

Obstructive sleep apnea is characterized by the relaxation of throat muscles during sleep, which obstructs the airway and results in frequent awakenings to breathe. This disruption can significantly lower oxygen levels, potentially causing harm to the brain's small blood vessels.

REM sleep is crucial for essential functions such as memory consolidation and emotional processing, making this relationship particularly concerning. According to the study, low oxygen levels during REM sleep were strongly correlated with cognitive decline, especially as indicated by changes in small blood vessels in the brain.

The investigation involved 37 participants with an average age of 73, all of whom were free from cognitive impairment and were not using sleep medications. The subjects underwent overnight sleep studies, during which their oxygen levels were monitored through all sleep stages, including REM sleep. Additionally, brain scans were conducted to assess brain structure.

Findings revealed that lower oxygen saturation levels during REM sleep corresponded with an increase in white matter hyperintensities--bright spots on brain scans that indicate damaged white matter tissue. This damage is typically a result of injury to small blood vessels in the brain. Minimum blood oxygen saturation levels and the duration spent below a 90% blood oxygen level were predictive of the extent of white matter hyperintensities present.

The researchers also analyzed the hippocampus volume and the thickness of the entorhinal cortex, both vital areas related to memory. A notable link was found between the presence of white matter hyperintensities and a reduction in volume and thickness in these regions.

Furthermore, participants underwent memory testing before and after sleep to evaluate sleep-dependent memory. The analysis indicated that deficits in memory performance were associated with diminished thickness in the entorhinal cortex.

These findings may shed light on the role of obstructive sleep apnea in accelerating cognitive decline related to aging and conditions like Alzheimer's disease through the deterioration of memory-supporting brain regions during sleep.

However, it is essential to note that the study's sample was predominantly composed of white and Asian individuals, suggesting that results may not be applicable across all demographics.

For more detailed insights, the full study can be accessed in the journal Neurology.