A systematic review with meta-analysis to assess Alzheimer's disease biomarkers in adults with or without obstructive sleep apnoea

Introduction

The aim was to design a meta-analysis evaluating the positron emission tomography (PET) uptake and cerebrospinal fluid (CSF), circulating levels of amyloid-β (Aβ), and tau proteins OSA group versus control group, as well as the association of these biomarkers with the severity of OSA.

Material and methods

Four databases were searched until April 17, 2023, without any restrictions. The effect sizes were the standardized mean difference (SMD) along with a 95% confidence interval (CI).

Results

A total of 21 articles were entered into the meta-analysis. The pooled SMDs of the CSF levels in OSA adults compared to controls were: –0.82 (P = 0.004) for Aβ42, –1.13 (P < 0.001) for Aβ40, 0.17 (P = 0.23) for p-tau, 0.04 (P = 0.65) for t-tau, 0.08 (P = 0.89) for Aβ42/Aβ40 ratio, and 0.81 (P = 0.001) for t-tau/Aβ42 ratio. The pooled SMD for the PET uptake of Aβ burden in OSA adults compared to controls was 0.30 (P = 0.03). The pooled SMDs of the circulating levels in OSA adults compared to controls were: 0.67 (P = 0.002) for Aβ42, 0.11 (P = 0.82) for Aβ40, 0.35 (P = 0.06) for p-tau, and 1.41(P = 0.005) for t-tau. The pooled SMDs for levels of Aβ42, Aβ40, total Aβ, p-tau, t-tau, and Aβ42/Aβ40 ratio in severe OSA adults compared to mild/moderate OSA adults were –0.15 (P = 0.33), 0.25 (P = 35), 0.04 (P = 87), –2.53 (P = 0.24), –0.24 (P = 0.52), and –0.28 (P = 0.30), respectively.

Conclusions

The results indicated that CSF levels of Aβ42 and Aβ40 in OSA adults were significantly lower, but the CSF level of t-tau/Aβ42 ratio and PET Aβ burden uptake in OSA adults significantly were higher than in controls.