Table 1_Associations between obstructive sleep apnea and Alzheimer's disease-related biomarkers (amyloid-β and tau) in blood and cerebrospinal fluid: a systematic review and meta-analysis.docx

In blood, OSA patients showed significantly higher T-Aβ (SMD = 0.66, 95% CI [0.34, 0.97], I² = 0%, p < 0.01) and T-tau (SMD = 1.48, 95% CI [0.33, 2.62], I² = 93.6%, p = 0.011). No significant differences were found for blood Aβ40, Aβ42, Aβ42/Aβ40 ratio, or P-tau. In CSF, patients with OSA had significantly lower Aβ40 (SMD = −1.13, 95% CI [−1.65, −0.60], I² = 0%, p < 0.01) and Aβ42 (SMD = −1.23, 95% CI [−1.84, −0.63], I² = 77.3%, p < 0.01), but no differences in Aβ42/Aβ40 ratio, T-tau, or P-tau.</p>Limitations<p>High heterogeneity, pre-dominantly cross-sectional designs, low-to-very-low GRADE certainty for most outcomes, retrospective registration, and limited study numbers preclude causal inference and warrant cautious interpretation.</p>Conclusions<p>This exploratory meta-analysis revealed compartment-specific associations between certain AD-related biomarkers and OSA.

However, given the low-to-very-low certainty of the available evidence and the substantial uncertainty reflected by prediction intervals that frequently crossed the null value, these findings should be regarded as hypothesis-generating rather than conclusive. Notably, the absence of consistent alterations in P-tau or the CSF Aβ42/Aβ40 ratio argues against a direct signature of established AD neuropathology. Future rigorously designed, large-scale prospective studies are warranted to determine whether these biomarker changes reflect early AD pathology or reversible physiological responses to OSA-related hypoxia and sleep fragmentation.</p><p>Systematic review registration:crd.york.ac.uk/prospero/display_record.php?RecordID=1148709, identifier CRD420251148709.</p>