Children who experience early adversity often show alterations across multiple stress response systems, including the hypothalamic–pituitary–adrenal (HPA) axis and autonomic nervous system (ANS). Changes in the diurnal rhythm of salivary cortisol (a marker of HPA axis functioning) and alpha-amylase (a marker of ANS functioning) may increase their probability of developing behavior problems. The goal of this study is to examine how these analytes may interact to predict externalizing behavior in infants exposed to early stress. Participants included 179 parents and their 6- to 20-month old infants recruited from a low-income neighborhood. Parents reported on their infants’ externalizing behaviors and collected saliva samples from their children at wake-up and bedtime over three days. Diurnal cortisol and alpha-amylase were modeled using latent difference scores. Four models were tested examining the effects of cortisol and alpha-amylase morning values and slopes, as well as their interactions, on externalizing behavior. Results showed a significant interaction effect of cortisol and alpha-amylase morning values, such that low morning cortisol was associated with decreased externalizing behavior when morning alpha-amylase was high but not low. These findings highlight the importance of examining multiple systems when characterizing the physiological correlates of externalizing behavior among infants experiencing adversity.

中文翻译：

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暴露于早期逆境的婴儿的外化行为和压力系统功能：多系统探索

经历过早期逆境的儿童通常会在多个压力反应系统中表现出改变，包括下丘脑-垂体-肾上腺 (HPA) 轴和自主神经系统 (ANS)。唾液皮质醇（HPA 轴功能的标志物）和 α-淀粉酶（ANS 功能的标志物）昼夜节律的变化可能会增加他们出现行为问题的可能性。本研究的目的是检查这些分析物如何相互作用预测暴露于早期压力的婴儿的外化行为。参与者包括从低收入社区招募的 179 名父母及其 6 至 20 个月大的婴儿。父母在三天内报告了他们婴儿的外化行为，并在他们的孩子起床和睡前收集了唾液样本。使用潜在差异评分对昼夜皮质醇和α-淀粉酶进行建模。测试了四个模型，检查皮质醇和α-淀粉酶早晨值和斜率以及它们的相互作用对外化行为的影响。结果显示皮质醇和α-淀粉酶早晨值有显着的交互作用，因此当早晨α-淀粉酶高但不低时，早晨皮质醇低与外化行为减少有关。