Short-term black carbon exposure impairs mental health and DNA methylation signatures of mitochondrial carrier genes.

Short-term black carbon exposure was significantly associated with increased depression symptom scores and higher odds of depression.

• BC exposure was associated with a 0.494-point increase in PHQ-9 scores
• BC exposure was associated with higher odds of depression symptoms (OR = 1.554, 95% CI: 1.276–1.901)
• Study population consisted of 2271 middle-aged and older adults from the Guangxi Eco-Environmental Health and Aging Study

Short-term black carbon exposure was significantly associated with increased anxiety symptom scores and higher odds of anxiety.

• BC exposure was associated with a 0.348-point increase in GAD-7 scores
• BC exposure was associated with higher odds of anxiety symptoms (OR = 1.628, 95% CI: 1.330–1.999)
• The study used the GAD-7 scale to assess anxiety symptoms

Good sleep quality mitigated the adverse mental health effects of black carbon exposure.

• Good sleep quality was defined as a Pittsburgh Sleep Quality Index (PSQI) score < 7
• The protective effect of sleep quality was observed for both depression and anxiety outcomes associated with BC exposure

Short-term (28-day) black carbon exposure was associated with DNA methylation changes at 113 CpG sites in mitochondrial regulatory genes.

• DNA methylation analysis was conducted in a subset of 573 participants with available methylation data
• 113 CpG sites in mitochondrial regulatory genes were significantly associated with 28-day BC exposure
• Three CpG sites were associated with PHQ-9 scores and five with depression symptoms
• 16 CpG sites were associated with GAD-7 scores and five with anxiety symptoms

DNA methylation at three CpG sites mapped on mitochondrial carrier genes SLC25A38, SLC25A37, and SLC25A35 mediated the impact of black carbon exposure on depression.

• Mediation proportions for these three CpG sites ranged from approximately 12.19% to 24.84%
• The three genes (SLC25A38, SLC25A37, SLC25A35) are mitochondrial solute carrier family 25 members involved in mitochondrial regulatory function
• Mediation analysis was used to establish the pathway from BC exposure through epigenetic changes to depression outcomes

The study identified a potentially modifiable biological pathway linking environmental black carbon pollution to brain health through epigenetic regulation of mitochondrial function.

• The findings suggest BC exposure affects mental health outcomes through epigenetic regulation of mitochondrial function
• Mitochondrial carrier genes were the key mechanistic focus, connecting air pollution exposure to neurological outcomes
• The study population was middle-aged and older adults, representing a potentially vulnerable demographic