sTREM2 mediates the associations of air pollution with depression and anxiety symptoms: The CABLE study.

BACKGROUND: Studies on air pollution and depression and anxiety have been reported, yet, the underlying mechanism of the associations remains unclear. We aimed to explore the correlations between air pollutants with depression, anxiety symptoms, and further explore the mediating roles of neuroinflammation and neuropathology. METHODS: 1202 cognitively normal participants were selected from the Chinese Alzheimer's Biomarker and Lifestyle cohort (CABLE). Multiple linear regression model was utilized to test the relationship between air pollution and depression and anxiety symptoms. Mediation model and structural equation model (SEM) were used to test the mediating effects of CSF sTREM2 and CSF amyloid pathology. RESULTS: The exposure of ambient PM2.5 was significantly associated with both higher score of depression (β = 0.254, p < 0.0001) and anxiety symptoms (β = 0.193, p < 0.0001). In contrast, ambient exposure of O3 was negatively associated with scores of depression (β = -0.088, p = 0.0040) and anxiety (β = -0.074, p = 0.0152) symptoms. Moreover, we found that the effect of PM2.5 on depression and anxiety was partially mediated by CSF sTREM2; and sTREM2 can further modulate the relationship between PM2.5 and depressive symptoms by influencing amyloid deposition. CONCLUSION: This study elucidated the correlations between PM2.5, O3, with symptoms of depression and anxiety. Neuroinflammation and amyloid pathology may serve as mediating factors in the association of PM2.5 with depression and anxiety symptoms.