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86. Disentangling Between and Within-Person Effects of the Bidirectional Associations Between Inflammatory Biomarkers and Depressive Symptoms
There is evidence for bidirectional associations between inflammatory biomarkers and depressive symptoms. However, extant studies have not explored whether it is differences in these factors between participants or changes in these factors within individuals that drive these effects. A sample of adolescents (N=140, Mage=17 y, 54% female, 59% black) completed the Children’s Depression Inventory and blood draws assayed for C-reactive protein (CRP), interleukin (IL)-6, IL-8, IL-10, and tumor necrosis factor-alpha (TNF-α) annually, resulting in 534 observations. Multilevel models were estimated with biomarkers predicting future depressive symptoms and vice-versa. Repeated measure predictors were separated into within-person and between-person components. Models controlled for BMI, medications, gender, race, and age. Between-person variance in log IL-6 had a moderate effect on depressive symptoms (β = 0.215, SE = 0.106, p = .043) and between-person variance in depressive symptoms had a small effect on log IL-6 (β = 0.153, SE = 0.066, p = .022). Log TNF-α had a small within-person association with depressive symptoms (β = 0.084, SE = 0.031, p = .008). This within-person effect could reflect a causal relationship between TNF-α and depressive symptoms. Additional results with symptom subscales will be discussed.