Emotional symptoms and inflammatory biomarkers in childhood: Associations in two Australian birth cohorts

Background: An increasing body of evidence supports associations between inflammation and mental health difficulties, but the onset and directionality of these relationships are unclear.Methods: Data sources: Barwon Infant Study (BIS; n = 500 4-year-olds) and Longitudinal Study of Australian Children (LSAC; n = 1099 10-13-year-olds).Measures: Strengths and Difficulties Questionnaire emotional symptoms at 4, 10-11 and 12-13 years, and circulating levels of two inflammatory biomarkers, high-sensitivity C-reactive protein (hsCRP) and glycoprotein acetyls (GlycA), at 4 and 11-12 years. Analysis: Adjusted quantile regression models examining cross-sectional associations between emotional symptoms and inflammation in 4 year-olds (BIS), and cross-lagged associations in 10-13-year-olds (LSAC).Results: We identified a small association between higher emotional symptoms at 10-11 years and higher GlycA levels a year later (standardised coefficient 13 = 0.09; 95%CI: 0.02 to 0.15). Sex-stratified analyses revealed this association was stronger for boys (13 = 0.13; 95%CI: 0.04 to 0.21) than girls (13 = 0.01; 95%CI:-0.09 to 0.11). These associations were not observed for hsCRP. There was little evidence of an association between higher GlycA or hsCRP at 11-12 years and emotional symptoms a year later, or cross-sectional associations between emotional symptoms and hsCRP or GlycA at 4 years.Limitations: A single time-point of biomarker collection in late childhood precluded adjustment for baseline inflammatory biomarkers.