Blood mercury and depressive symptoms: a longitudinal study combining metabolomics

Abstract

Mercury exposure may increase the risk of depression. This study aimed to examine the association between blood mercury and depressive symptoms in Chinese young adults. We collected 477 fasting venous blood samples and questionnaire data from the Chinese undergraduate cohort study in 2019 and 2021. Patient Health Questionnaire-9 was used to estimate depressive symptoms. Blood mercury levels and metabolomic levels were measured using inductively coupled plasma mass spectrometry (ICP-MS) and liquid chromatography-mass spectrometry. Using linear mixed-effects models and ANOVAs based on baseline blood samples (N = 468) to examine metabolomic changes associated with mercury exposure. Our study found for every 2-fold increase in blood mercury levels, the depression scale score increased by 0.50 [95% confidence interval (CI): 0.14, 0.86]. And in males, a 2-fold increase in blood mercury levels was associated with a 0.87 (95% CI: 0.12, 1.61) increase in depression scale scores, while it wasn’t observed in females. Individuals consuming fish ≥ once a month shows similar negative correlation. Metabolomic analysis identified 10 differential metabolites enriched in 4 metabolic pathways. Blood mercury may deteriorate depressive symptoms. Males and those who consume more fish are susceptible subjects. Mercury exposure may affect depressive symptoms through neurotransmitter, energy and inflammation-related pathways.