Associations of Plasma Total Tau Level and MMSE Score With Polysomnographic Data in Middle-Aged Men With Severe Obstructive Sleep Apnea: A Pilot Study.

BACKGROUND: Obstructive sleep apnea (OSA) is one of the most common sleep disorders. Intermittent nocturnal hypoxia and sleep fragmentation in OSA may be among the main mechanisms triggering cognitive impairment and neurodegeneration. The study was to identify the relationships among plasma total tau (t-tau) levels, Mini-Mental State Examination (MMSE) scores, and sleep parameters in middle-aged men with severe OSA. METHODS: Twenty-three men (mean age, 52.3 ± 2.2 years) with severe OSA were included. Nineteen age-matched men without OSA served as controls. All participants underwent overnight polysomnography (PSG). Global cognition was assessed using the MMSE. Plasma t-tau levels were measured by enzyme immunoassay. Pearson correlation analysis was used to assess the relationships among plasma t-tau levels, MMSE scores, and PSG data. RESULTS: Plasma t-tau levels were significantly negatively correlated with non-rapid eye movement sleep stage 3 (N3) duration and mean oxygen saturation (SaO2) and positively correlated with the apnea-hypopnea index (AHI), oxygen desaturation index (ODI), and arousal index (AI). MMSE scores were negatively correlated with AHI, ODI, and AI. CONCLUSION: Reduced deep sleep duration, nocturnal intermittent hypoxia, and sleep fragmentation were associated with a greater t-tau burden and lower MMSE performance in severe OSA.