Association between obstructive sleep apnea and Alzheimer's disease-related blood and cerebrospinal fluid biomarkers: A meta-analysis

Introduction: Recent studies indicate that Alzheimer's disease- (AD) related biomarkers, including amyloid beta (A beta 40 and A beta 42) and tau proteins (P-tau and T-tau), in blood and cerebrospinal fluid (CSF) are associated with obstructive sleep apnea (OSA). However, the results have been inconsistent. Therefore, the primary purpose of this meta-analysis was to determine the relationship between blood and CSF AD-related biomarkers and OSA. Methods: We searched the Embase, PubMed, Scopus, and Cochrane Library databases for relevant articles till February 2022. Results: Eight articles were finally included after the literature screening, including 446 patients with OSA and 286 controls. Pooled analysis showed that CSF A beta 42 (SMD = -0.220, P = 0.136), T-tau (SMD = 0.012, P = 0.89), and P-tau (SMD = 0.099, P = 0.274) levels were not different between patients with OSA and controls. In patients with moderate to severe OSA, CSF A beta 42 (SMD = -0.482, P = 0.031) were significantly lower than in controls. Blood T-tau (SMD = 0.560, P = 0.026), P-tau (SMD = 0.621, P < 0.001), and A beta 40 (SMD = 0.656, P < 0.001) levels were significantly higher in patients with OSA than in controls. Blood A beta 42 (SMD = 0.241, P = 0.232) were not different between patients with OSA and controls. Conclusion: OSA is associated with changes in AD-related markers. Higher OSA severity may be associated with the development of AD. AD-related biomarkers, especially in the blood, are clinically efficient, less invasively assessed and monitored, and may be useful for detecting OSA and related cognitive impairments. Further studies are needed to confirm these results.