Associations Between Objective Sleepiness and Cognition Function Before and after CPAP in Obstructive Sleep Apnea Patients

Objective: To examine the association between objective sleepiness and neurocognitive function before and after continuous positive airway pressure (CPAP) in obstructive sleep apnea (OSA) patients. Methods: A total of 53 patients with overnight polysomnography (PSG) determined moderate-to-severe OSA (apnea hypopnea index (AHI) ≥15 events/h) and with overnight CPAP therapy from West China Hospital, Sichuan University within the period from Feb 2018 to Dec 2018 were enrolled in the study. At the baseline, all patients underwent overnight PSG study, multiple sleep latency test (MSLT), psychomotor vigilance test (PVT), and Epworth sleepiness score (ESS). After CPAP therapy, all patients underwent MSLT and PVT. Paired nonparametric test or t test were used to compare the differences between daytime sleepiness and PVT performance before and after CPAP. Results: Compared with baseline data, AHI [68.8(42.2, 80.0) vs 7.4(3.1, 11.1) events/h, P<0.05] decreased, the percentages of non-rapid eye movement stage 3 sleep time [0(0, 0.5%) vs 4.4%(1.9%, 11.3%), P<0.05] and the percentages of rapid eye movement sleep time [18.6%(13.2%, 22.7%) vs 25.4%(23.85, 30.3%), P<0.05] increased after CPAP therapy. The reaction time (RT) [353.0(317.5, 429.5) vs 333.6(309.7, 381.4) ms, P<0.05], the slowest 10% RT [602.9(473.2, 841.3) vs 505.5(431.6, 618.8) ms, P<0.05] and the fastest 10% RT [260.8(236.6, 300.6) vs 251.4(233.6, 283.2) ms, P<0.05] shortened, and the lapse [6.0(2.5, 16.5) vs 3.0(1.0, 8.5) events, P<0.05] decreased. The mean sleep latency (MSL) [5.8 (3.4, 8.3) vs 7.5(4.7, 12.4) min, P<0.05] increased. The changes in PVT parameters [ΔRT (r=0.20, P>0.05), Δslowest 10% RT (r=0.15, P>0.05), Δfastest 10% RT (r=0.24, P>0.05), and Δlapse (r=0.15, P>0.05)] were not correlated with the change in MSL. The significant association between the slowest 10% RT and ESS was found in baseline data. Conclusions: The change in MSL is not associated with the change in PVT performance before and after CPAP therapy. MSLT and PVT may be different in nature.