Abstract

Introduction: In the elderly population, the association between obstructive sleep apnea (OSA) and cognitive decline is still controversial.

Objective: To test whether baseline OSA is associated with 5-year cognitive decline in the community-dwelling elderly population.

Methods: We studied participants aged ≥65 years who underwent polysomnography and cognitive assessment at baseline, followed by a second cognitive assessment 5-year apart. OSA was defined by an apnea-hypopnea index ≥15/h. The cognitive assessment included six neuropsychological tests. The primary outcome was the change score of each test over the follow-up. The moderator effect of age, sex, and apolipoprotein E4 was examined. Analyses were adjusted for demographic, genetic, and clinical confounding factors.

Results: The sample included 358 participants (mean age 71.0±4.1 years, 42.6% men). OSA was associated with a steeper decline in Stroop Test Condition 1 (B=5.48, p=0.005) in older participants only (≥74 years) and with a steeper decline in phonemic fluency (B=-3.52, p=0.002) in men only. Participants with mean oxygen saturation during sleep ≤92.5% had steeper decline in Mini-Mental State Examination (B=-0.53, p<0.001), Stroop Test Condition 1 (B=2.94, p=0.001), and Free & Cued Selective Reminding Test (B=-0.77, p=0.006). Spending ≥4.5% of sleep time with oxygen saturation <90% was associated steeper decline in Stroop Test Condition 1 (B=2.64, p=0.004).

Conclusions: In community-dwelling elderly, OSA was associated with a steeper decline in processing speed and executive function, but only in older participants and men. Hypoxemia was associated with a steeper decline in global cognitive function, processing speed, and memory.