On August 11, a paper titled “Impact of Sleep Apnea on Perivascular Diffusivity and Cognition: A 4-Year Prospective Cohort Study” was published by Chang-Ho Yun from Seoul University in the Annals of the American Thoracic Society. The study found that obstructive sleep apnea (OSA) may lead to cognitive decline by affecting perivascular diffusivity (similar to lymphatic glymphatic system function).
The study tracked 1,110 community subjects over a period of 4 years, using polysomnography, brain diffusion tensor imaging (DTI), and cognitive function assessments. It was found that: the severity of OSA (measured by the apnea-hypopnea index AHI) was significantly negatively correlated with perivascular diffusivity (DTI-ALPS index). For every increase of 1 event/hour in AHI, the baseline DTI-ALPS index decreased by 0.008, and further decreased by 0.007 after 4 years (P<0.001). The group with worsening OSA exhibited the most significant decline in perivascular diffusivity.
This study is the first to confirm that changes in perivascular diffusivity mediate the relationship between OSA and cognitive decline. Improvements in the DTI-ALPS index were significantly associated with enhancements in visual memory function, including immediate recall (β=0.401), delayed recall (β=0.351), and recognition ability (β=0.145). Changes in perivascular diffusivity mediated the impact of AHI changes on visual memory, explaining 15-21% of the variance (P<0.001).
This research provides a new pathophysiological explanation for cognitive impairment caused by OSA, specifically through its impact on the fluid dynamics of the brain’s glymphatic system. The DTI-ALPS index may serve as a novel imaging biomarker for assessing cognitive risk in OSA patients. This finding provides a theoretical basis for developing treatment strategies targeting the glymphatic system in OSA.