Relationship between Serum Neurotransmitters and Cognitive Impairment in Adults with Obstructive Sleep Apnea.

Introduction: The primary aim of this study was to investigate the serum levels of acetylcholine (Ach), norepinephrine (NE), dopamine (DA), and 5-hydroxytryptamine (5-HT) in two groups: those with obstructive sleep apnea (OSA) and cognitive impairment (CI) and those with OSA but no cognitive impairment (NCI).

Methods: A total of 30 adults (CI) and 75 adults (NCI) who completed polysomnography examinations between December 2023 and September 2024 were enrolled in the study. Enzyme-linked immunosorbent assays were used to measure serum levels of Ach, NE, DA, and 5-HT. Correlation and pooled analyses were conducted to assess the relationship between cognitive scores and four serological indicators. Logistic regression was performed to identify risk factors for cognitive impairment.

Results: Serum DA levels were higher in the CI group (275.10, 216.73-426.91, pg/mL) than in the NCI group (219.69, 138.46-261.97, pg/mL) (P < 0.001). No significant differences were found in serum NE, 5-HT, and Ach levels between the two groups (P = 0.582, P = 0.287, and P = 0.715, respectively). Moreover, the correlation analysis showed a correlation between DA and body mass index, Montreal Cognitive Assessment, average saturated oxygen (SaO₂), minimum SaO₂, the percentage of oxygen saturation less than 90% (all P < 0.05). The area under the receiver operating characteristic curve of DA was 0.732 (95% confidence interval: 0.628-0.836) (P < 0.001). Logistic regression analysis revealed a correlation between tonsil size, hypertension, DA, stuffy nose, and cognitive impairment.

Conclusion: Serum DA levels were associated with the severity of cognitive impairment in adults diagnosed with OSA and might serve as a potential, objective biomarker for identifying cognitive dysfunction in this population.