A multidimensional narrative review of the association between air pollution and late-life depression risk

Synthesizing evidence from 80 empirical studies identified through a systematic search of Web of Science, this review highlights the association between air pollution exposure and late-life depression. Results indicate that exposure duration is a critical modifying factor: acute, short-term exposure correlates with symptom exacerbation, whereas long-term, cumulative exposure is linked to increased incidence. Pronounced geographical heterogeneity emerges, with larger effect estimates consistently reported in highly polluted regions. Critically, significant associations persist even in low-pollution settings like Sweden, challenging the notion of a safe exposure threshold. Furthermore, neurotoxic effects vary markedly across pollutants, with PM_2.5 (and its specific components), NO₂, O₃, and indoor solid fuel combustion demonstrating particularly pronounced associations. Potential synergistic effects between indoor and outdoor sources are also suggested. In conclusion, air pollution constitutes a significant and modifiable environmental determinant of late-life depression. Future efforts should integrate multidimensional exposure assessments into urban planning and public health policy, implementing targeted interventions for vulnerable populations to simultaneously improve environmental quality and mental health in later life.