Abstract
Childhood maltreatment has been associated with increased inflammation, as indicated by elevated levels of proinflammatory markers such as interleukin-6 (IL-6) and C-reactive protein (CRP). Studies in humans show that secretion of IL-6 follows a clear circadian rhythm, implying that its disturbed rhythm represents an important aspect of dysregulated inflammatory system. However, possible alterations in diurnal secretion patterns of IL-6 associated with childhood maltreatment have not been studied. Here we investigated this association in 116 healthy adults. Diurnal levels of IL-6 were examined using saliva samples collected at 5 times a day across 2 consecutive days. Salivary CRP levels were also determined by averaging measurements at 2 times a day for 2 days. Different types of childhood maltreatment were assessed with the Childhood Trauma Questionnaire (CTQ). CTQ total and emotional abuse scores were significantly correlated with smaller IL-6 diurnal variation as indexed by lower standard deviation across the measurement times (p = 0.024 and p = 0.008, respectively). Individuals with emotional abuse, as defined by a cut-off score of CTQ, showed flatter IL-6 rhythm than those without (p = 0.031). These results, both correlation and group comparison, remained significant after controlling for age, sex, and body mass index. Childhood maltreatment was not associated with total output of IL-6 or CRP. Our findings indicate that childhood trauma can have a long-term negative effect on the circadian rhythm of inflammatory system. The findings are consistent with those of previous studies on adulthood trauma, suggesting that the disrupted IL-6 rhythmicity may be associated with a broad range of trauma-related conditions.