OBJECTIVES
Sleep-disordered breathing (SDB) is a group of disorders common among older adults, characterized by breathing pauses during sleep often accompanied by hypoxemia. Few studies have examined if SDB is associated with cognitive decline.
DESIGN
A population-based longitudinal study.
SETTING
6 centers in the United States.
PARTICIPANTS
2,636 community-dwelling older men (age 76.0 ± 5.3 years) without mild cognitive impairment, followed 3.4 ± 0.5 years.
MEASUREMENTS
SDB, measured by in-home polysomnography: nocturnal hypoxemia [≥1% of sleep time with oxygen saturation (SaO2) <90% vs. <1%; oxygen desaturation index (ODI: number of oxygen desaturations ≥3% per hour sleep)]; apnea-hypopnea index (AHI, number of apneas and hypopneas at ≥3% desaturation per hour sleep). Cognitive decline, measured by the Modified Mini-Mental State examination (3MS) and Trails B test at baseline and 2 follow-up timepoints. Associations of predictors and cognitive decline were examined with linear mixed models adjusted for multiple confounders. Models were further adjusted by potential mediators (sleep duration, sleep fragmentation, resting SaO2).
RESULTS
Nocturnal hypoxemia was related to greater decline on the 3MS. Men with ≥1% of sleep time with SaO2<90% had an adjusted annualized decline of 0.43 points compared to 0.25 for men in the referent group (P = .003). For each 5-point increase in ODI there was an average annualized decline of 0.36 points (P = .01). Results were robust to further adjustment for potential mediators. The association between AHI and cognitive decline did not reach significance. No associations were seen with SDB and decline on the Trails B test.
CONCLUSION
Among older community-dwelling men, there was a modest association of nocturnal hypoxemia with global cognitive decline, suggesting the importance of overnight oxygenation to cognitive function.